Spark - Life gain on hit, or life leech?

The questions fairly simple, with a blood magic spark build, would it be better to use Life gain on hit or Life leech?

I'm not sure about the mechanics behind both of the support gems, and would love to know more about them so i can decide these sorts of things for myself in the future

Thanks in advance :)

I think life gain on hit Will be best since spark are alot of small little balls that will hit often i mighty be wrong i am not sure

If I am not mistaken, LoH does not work with spells. Life leech would be your only option with Spark.

Even then..spark is a very low DPs spell..not going to generate lot of life steal

I would imagine a LOH support gem would work on it. I'd advised LOH over leech, since you've got many little spark balls bouncing around. It works great with split arrow+fork as well.

LoH does not work on spells since it only works on attacks. Thus Lif leech is the right choice.