First off, I will not state whether either skill/build is better, because they are both situational and have there pros and cons, which I will state later. This is merely a comparision of the two skills and the builds that accompany them.
Spit
- Mana Cost: 500/650/800/950
- Damage: 50/100/150/150 initial damage + 450/800/1150/1500 damage over 10 seconds
With Putrid Flow: + 500 AoE damage over 5 seconds
- DPS: 45/80/115/150 over 10 seconds + 50/100/150/10 initial damage
With Putrid Flow: + 100 DPS over 5 seconds
Spit Build
1) Kill Potential: With a greater range, speed, and damage output a spit UB will have a much easier time getting kills.
2) Lane Pushing: Spit is a great weapon against buildings in addition to enemy DG. While you won't be able to push as effectively as a Rook, you can still get the job done.
3) Intimidation: People are often very afraid of spit, and will try to run when it hits them. This is when you hunt down and kill them with AA or a second spit.
4) Misjudgement: It can be very hard to tell exactly how much damage is coming from spit, and how much is coming from UB's AA. As such your opponent can't be sure that they could still take you on even if they can disable your spit until they actually try, which can be a fatal error.
1) Squishy: Despite the fact that it is easier for you to get kills, it is also easier for you to be killed, as you will(presumably) not be stacking as much +health and health regen as an ooze UB. Even if you win the fight, you will probably have to go back to the health crystal to heal.
2) Counters: Spit has about 6 counters, including but not limited to: Oak's Shield, Sedna's Heal, QoT's Bramble Shield, Erebus' Mist, Symbol of Purity, and plain health stacking.
3) Mana: Spit is a fairly mana intensive skill, and you won't be able to use it more than twice without a +mana item. This problem is compounded if/when you decide to get Foul Grasp.
Ooze
- Range: Unconfirmed AoE(6 yards?)
- Attack Speed Reduction(percentage): 10/20/30/40
Ooze Build
1) Survivability: With the combination of health, armor, and hps you have a lot of staying power, making it extremely difficult for enemies to kill you. Turning off ooze to regain health after a fight through hps can quickly get you back to fighting condition. It is unlikely that you will have to return to your base except to buy new items.
2) Mana: The only skill a ooze build will pick up that costs mana is Foul Grasp for the interrupt. You will almost never have to worry about running out of mana to use it, since Foul Grasp will only be used to interrupt an annoying skill, stop a teleport scroll, etc.
3) Team Support: Ooze is an AoE ability, causing damage to all enemies in the immediate area as well as reducing their attack speed. In a fight between 2 DGs on each side, ooze will save both your life and your teammate's.
1) Health Loss: One of the most obvious problems with ooze is the health cost. An ooze build has to continously upgrade its +hps items in order to keep up with the loss of health. If you don't start getting kills soon after the game starts to afford the items needed to counteract ooze you're screwed.
2) Range: Another obvious problem is the complete lack of range. You will lose kills that you could have gotten with spit. If your opponent is fast enough to run away from you, even with diseased claws, killing him will be frustrating to say the least.
3) Lane Pushing: An ooze UB is the worst pusher in the game until mid-game at the earliest, when you have stacked enough armor and hps to destroy a tower and take almost no damage. This adds to the range problem, as you can't take out a tower early-game to give yourself more space to kill your target without help from an ally.
Well that's it, thanks for reading. I apologize if anything in here is too messy, I'll probably clean it up and add to it later. If you see a mistake or disagree with a point I made feel free to point it out.