I will put tower following a certain rank.
I. GOD Tier
1. Mr.Iron: Even after his nerf, this tower stays as one of the most important of the game:
He is an insane support: he gives to your carry ad,as,crit%
He is an inasane late carry: Even if he has a lower range/ low dammage, he can have an insane attack speed
He is the only tower able to handle air wave without any problem (stacking long bow)
And It's the only carry tower who doesn't trully need potion to be average
Overall, he must be tower on this game
2.Knusperhexe: Even after his nerf, this tower still give an nice armor penetration for your carry tower:
He also clear mass wave like butter, with 100% kill late game
Combine this 2 tower to disable 2 groups of monster from the bonus wave (in part at least)
3. Shadow: He got an nerf from his based dammage but stays as the only tower adaptating while the game go on, making him the current strongest tower ULTRA-Late game
4. Holgar the Horrible: even after his nerf, he's giving out some nice bonus mid/late game
His helm is one of the few item giving luck for your tower
His potion still makes you snowball by transmuting them
5. Manitou: +2multi-crit what else? It's one of the most important tower to win
The God Tier tower are most of the time, the tower you're going to use of your run (of course you won't b able to have shadow & holgar at the same time since both of them are hard carry tower)
II. Above average Tower
1. Miss Jilly: is able to assassinate any no-Boss creep who's good late game
2. Beaver: for the stunt on monster, average tower early/mid game
3.ganesha & the dark forge: Combo tower to give out free item
4.GIB,The Frozen Daemon: Free slow with reaver, helping carry to clear
6. Hitman: Scale so well mid/late game with his range, crit, dammage (even if random)
III. Average Tower
1. Dandelion: 33% increase doesn't seems a lot, but some aoe is helping early on and his passiv still help mid game
2.Baby Rabbit: Nice overall tower, medium damage,range,speed, and dual/trial attack. Making this tower not bad as not good either.
3. Herb Witch: Nice early buff when most of the tower lack of attack speed
4. Irish Pub: Nice early tower with his new active, scale well mid game but fall of late game since his active won't be so usefull
5. Elvis Imitator: Giving some nice slow if you're tower are low range but then giving an strong mouvement speed. That why this tower is lower than GIB
6.Scarecrow & poisonous frog: good eearly/mid tower to clear challenge
IV. Bellow Average
1.Huli The Monkey: This tower can have an insane attack speed but he's lacking of dammage late game, since a lot of tower will easily outscale him
2.Muli The Evil Twin: Same as Huli even if he scales a bit better, he's limited by bananas :/
3. Bear Hunter: Same as Huli, this tower is getting outscale way too easily. The trap is a nice idea but it's not strong enought to be an hard carry tower
4. Balu The Bear: An very good AOE clear, but his cooldown is way to hight to be effective. And a very mediocre passiv/rang
5.Scientist: It seems as a good tower, free xp but the ammount is really low. How ever I tried, this tower isn't very effective but can sill remplace an future support tower
6.Electric chair: Actually this tower isn't so bad, but he's lacking of something: attack speed
What do I mean by that? This tower is one of the strongest wave clear but his attack speed make it an rally bad tower early/mid game. And when we're going to the late game, she's alrady out-scaled by any other
7.Horadric Cube: Free pot what else? Even when you build it, this tower isn't so great
V. Hell Tier
1. Wolf: Low range,attack but nice attack speed. An okay passiv... But who the hell would make multiple carry tower <- not viable
2. Pocket Thief: 25% 3/6/9gold? Seens nice early if you're lucky. But on the other hand, (4*2)sec= gold early
you would need 16 proc to retrive your gold so arround 64 attack. Then his kit isn't so good, and gold isn't a problem during the game
3. Money Bin: Who need more gold? Who need more income? This tower isn't as good as it was. And alone his stats isn't making her effective
4. Scarface: This tower seems not bad but really, if you're going to use it, you cannot put him where ever you want and he's lacking of boss kill potential. So not viable
5. BloFeld Laser Satellite: OMG This tower hit for 5k based dammage late game it's insane!!! But each shot make you loose X% damage. So leave it 5min on an bonus wave and you won't be as surprised as before. Making him also not viable
6. Black Widow: Nice an aura that give item! But actually the pot are doing it way better, Gold? not needed. 2xp/kill? Not so interesting either. Overall, this tower isn't good unless you're cursed (no drop)
So as I see the game, a meta is already made. There is only a few tower able to scale late game. The rest of them are mediocre.