My Personal Overview of Land Units

Swordsmen

Defensive Nuke => 2000 sw + 125 Fast Transports

Best unit for defending against distance attacks (slingers). The most common defensive unit in any world. Weak against sharp attacks (hoplites, chariots, manticors). When setting up my own LTS, I generally follow the ratio of 5 swordsmen, 4 archers, 3 hoplites for a fair balance, but still heavier on the distance defense as slingers are the most common offensive unit of all time. Though they use no stone to build them, rebuilding them can have their advantages. I can send all of that unneeded stone over to my slinger nuke cities to help rebuild them while not hurting myself for resources.

Archers

Defensive Nuke => 2000 arch. + 125 Fast Transports

Best unit for defending against sharp attacks (hoplites, chariots, manticors). More expensive than swordsmen, but still a far cry from the cost of hoplites. Personally, I keep a bunch of these around in frontline cities with fast transports so as to be able to support CS's we've landed in enemy cities. Also useful in helping to snipe enemy CS's as its common to send a hoplite or chariot nuke (otherwise known as a hybrid nuke) with the CS attack. A personal preference is to build a nuke of 2000 archers + Fast Transports in a "middle line" city. (insert link for city categorization based on location)  This can be a lifesaver when dealing with enemy manticor nukes that are trying to break a siege you and your team are trying to hold.

Hoplites

Defensive Nuke => 2000 hops. + 125 Fast Transports

Offensive Nuke => 1800 hops. + 113 Fast Transports + 30 LS

Cheapest of the 2 "hybrid" units, a hoplite nuke is the cheapest and most cost effective sharp nuke. Definitely needed for taking out the myriads of swordsmen that most people build for defense. Takes a TON of silver to build and no wood, so be wise with your hoplite nukes as it'll take forever to rebuild them. Beauty of a hoplite nuke is that it can be used to defensive or offensive snipe enemy CS's. Also, they are the best counter (besides myth units) to horsemen nukes. Their greatest weakness is the most common offensive unit, slingers. So be very careful where you leave them. If you take a look at the stats on hoplites and chariots, you'll see that while they are "hybrid" units, that comes with a price. Neither has stunning offensive stats, and both have very defined weaknesses. So when I build them, I decide before hand what I'll use them for (offense or defense) and I try hard to stick to that as if you try to do both, your setting yourself up to be short on offense or defense when it might make a huge difference one way or the other. Personally, if in a danger zone, I would "hide" them while I'm offline if I'm using them for offense. Click here to read my guide about "hiding" nukes.

Chariots

Defensive Nuke => 500 char. + 125 Fast Transports

Offensive Nuke => 400 char. + 100 Fast Transports + 40 LS

Although popular, they are practically one of the most costly and cost-inefficient units in the game. Eats up a TON of resources and population for not that much of a punch. Would personally only build a nuke of these to escort a CS where there is a chance of having something to kill on attack, and then an attempt at a offense snipe after the CS lands. Otherwise, building a nuke of hoplites would be your better bet if your looking for a effective sharp nuke. The only reason a lot of these get built is because their "flashy". The use some of each resource, stone more than anything. To a lot of people, they like spending resources "equally" as it has more appeal. But this can be a HUGE downfall as a chariot nuke is easily taken out while on the offense by a couple hundred archers and on the defense with a hoplite nuke. So my final verdict - don't bother with them and use something more cost effective. (see first comment below by a good friend of mine for a slightly different opinion and how he uses them)

Slingers

Offensive Nuke #1. => 1400 sling. + 25 catapults + 111 Fast Transports + 30 LS

Offensive Nuke #2. => 1900 sling. + 119 Fast Transports + 20 LS

Personally, my favorite unit of all time. Stat wise, they are the cheapest and most cost-effective attacking unit in the game and as an additional bonus, the require what all of us overflow in. Stone! Generally, I'll build slinger nukes from the size of 1200 + 20 catapults - 1900 and a reduced LS escort. The bigger the nuke, the more effect they are going to be (assuming that they make it ashore). Compared to the "hybrid" units, slingers have NO defense to speak of. So, if at all possible, DO NOT defend with them. Slinger nuke vs. slinger nuke is the most effective way of taking out an opponents slinger nuke. While I've been tempted to have only slinger nukes for my offense, the thought of thousands of swordsmen waiting for me quickly destroyed that idea. Though a good portion of my offense ends up being slinger nukes, I also try to throw in several hoplite nukes and my second favorite offensive nuke, a horsemen nuke. Slingers are definitely cheaper and more cost effective, but many times you need to adapt to what the enemy city is weak in and take them out that way, otherwise your going to waste a lot of troops against a defense that is especially strong against what you've foolishly mass produced. So while they are the best attacker, don't go overkill in building them and have some variation to your offense.

Horsemen

Offensive Nuke => 600 horse. + 113 Fast Transports + 30 LS

Without a doubt, ranked my 2nd favorite attacker. Horsemen are the best land unit when it comes to farming. They excel in killing archers, and they do fairly well when going against swordsmen. While not super expensive, they still are a bit spendy. With all their good-points, there always comes some negative aspects. #1. They have NO sharp defense. (or any other defense to speak of) When caught napping by a sharp nuke, horsemen will just roll over and die. So be sure if you have a horsemen nuke in a danger zone (insert link for definition of danger zone etc.) that you hide while your offline or you might find yourself giving the enemy easy bp's for not much return. In every world, you'll always find "turtles" that will go all defense and turn many of their cities into in-penetrable fortresses. Lucky for us, we have the good old horseman nuke to crack them with. Generally, the weakest point in any turtled-up city is blunt defense, but always check first as they might be aware of this and leave another area weaker. Above all though, be careful of hoplite, chariot and pegasus nukes as they'll turn your horseman nuke into a scrambled egg. But overall, horsemen nukes are very powerful and can be a lifesaver when it comes to cracking stacked cities.

Catapults

Offensive Nuke => You should NEVER build a catapult nuke. Read below to see why.

While powerful looking, nothing could be further from the truth. By themselves, catapults are HORRIBLE attackers. The game mechanics dictate that in a battle, catapults attack the wall while the units escorting them keep the defenders busy. But, the theory that the more catapults, the more damage, is completely off-base. I'm personally seen a full GOU nuke smash into my cities escorting +30 catapults and the most they destroyed was 1-2 wall levels. The reason.... the escort didn't keep all the defenders busy and it appears that most of the catapults got "destroyed" before they got a chance to bring any wall down. Besides being super expensive, taking up a lot of population room, catapults are SUPER slow when traveling across land giving the defending possibly and hour or 2 to get more defense into the city before your attack finally arrives. So, the best bet for using catapults is to build 10-20 to go along with a slinger nuke. I've never tried building them to go with a horseman or hoplite nuke, but I've seen others do it with the same results as with a slinger nuke. 

Consequently, the more LDU that is in the defending city, the less effective = less damage your catapults will do. However, if the defender dodges your attack, your catapults (assuming you have 20 in with your nuke) will practically level the wall. This is all great if your just attacking for the sake of killing the enemy and trying to destroy their wall, BUT, if you intend to attempt to conquer the city, you just destroyed the wall that would help you once you land against attempts to break the siege by land or myth nukes. So, use catapults very wisely. If you have a CS enroute to a city, I would HIGHLY recommend NOT sending catapults and letting your fellow alliance members know that as well so one of them doesn't accidentally shoot your siege in the foot before it ever gets started. If it happens that you can't hold the siege and have to pull it out because of the wall being down, some good can come out of that depending on the situation. If you can't hold it, that means the owner is going to have a hard time holding it against you until he gets that wall back up, so you opened the door for at least one more opportunity. (assuming the harbor doesn't get stacked with BR's)

So overall, I use catapults sparingly and definitely DON'T build them with most of my GOU nukes.