Well, lets look at your options:
Life on Hit:
Every hit gives you a percentage of your Loh based on which attack you used. If your attack CAN hit multiple targets(even if it doesnt), it usually has an awful coefficient. For example blizzard gives you I think 0.05% of your life on hit. Hydra gives you 0%. arcane orb gives you like 60% or 40% if you rune for it to go through people, so all in all its pretty poor.
In the end, it helps and might be good for some builds, but for most it just is underwhelming. Don't avoid the stat, but I wouldn't sacrifice muchf or it.
Same deal, same coefficients, + 80% reduction for inferno. Again, hardly noticable..helps a little sometimes but just isnt that good. For example I did the raknaroth cheese strat where you stay at under 30% armor and make it so you can never die. It took almost the entire fight for life on hit to push me up the few % needed for him to kill me.
Life over time
Probably my favorite. It's slow but it works well with kiting -- You're constantly healing, so if you get hit you just need to be a little more careful for a little bit of time. The main drawback is there is a pretty solid cap on how much damage you can take, so you'll never be able to "upgrade" to the point of sitting in a bunch of damage and healing your way through it a way a monk can.
Honorable mention: Plus healing globe health
I somehow got like +10k to my health globes, so if I see one its pretty much a full heal. Really nice, but not something you can depend on.