Melee players get hit a lot, they also have neat tricks like life leech on hit and great regen so Health is the way to go.
Casters have neat tricks for FS regen and gear feeds them FS so that is a great choice.
Ranged characters that get close once in a while are fine with either, but use a mix of health/Force Shield very well.
I'm melee and I have been focusing mostly on "ALL RESISTANCES" for gear and as much health as I can grab, I'm over 11k health with 51-54% resists feeling good just starting excursions.
I do have 1000 force shield, but that just came from gear I haven't upgraded yet or the gear has other appealing options with it.

Good luck!