Simple question, read the title. Try to back up your answer with info. Either the path which gives most quests completed/enemies killed, etc.

Thanks to anyone who can answer.

NCR has the most quests without any doubt, though you could do an Independent or House playthrough while also doing the bulk of the NCR quests. Its a hard question to answer without more detail since New Vegas is incredibly non-linear.

Independence itself potentially has the most since you visit every tribe, but it's all perspective.
For example if you tag on the NCR side quests to an NCR main quest playthrough then that might be more, but there's certainly nothing stopping you from doing all of those in an Independent playthrough, nor is there anything stopping you from doing the Independent path in the shortest way possible, making for the least amount of EXP.

Probably independent or NCR (but outside of role-playing who would want something that will destroy itself for the mojave?)

In the Independent route you have to interact with every main faction and deal with the ncr president, thou you could just visit their camps and let the ncrs poresident be shot by some legionaire and be done with it.
NCR you have to interact with 5 or 6 factions and save their president