look at dirty white boy build. i'll post the link in a min, its done w/ leafs.. leafs are cheap and can be very effective. think about it, most toyota crawlers are done w/ leafs. YJ's can be great offroad and they are leafs. most newer rangers are done w/ leafs when sas'ed (the torsion bar non coiled ones). with the right leafs, like trail gear yota's or yj lift leafs.. you can get good flex.
coils are better if a daily driven rig IMO. to do coils, ideally you'd use extended radius arms and some good flexy coils, like xj coils. but this route is very expensive compared to leafs. think something like a rusty's long arm kit on a wrangler.. coils are newer tech stuff, and will probably net more flex.. but you get what you pay for. look into early bronco coils for this. deaver's or skyjacker or whatever. this can be done cheaply if you find deals and do the fab work like radius arms yourself.. also depends on what your axle is already set up for to.. its easier to use coils on an axle set up for coils. less work. lol.
what are you overall plans? strictly trial use? do leafs for the cheap/easy/effective way out. you want a good smooth ride for daily use/ weekend trail awesome-ness? do long arms and coils.