I'll fly, spin, cast, troll, deep rig, or what have you depending upon the situation.
Fly fishing pisses me off more than anything. More that golf. It takes skill and patience and knowledge and luck.
Spin fishing is the most well rounded. The easiest, and I find myself doing more of it of late because of that.
Bait casting is the "in-between" of fly and spin. Depends on the situation. My least favorite.
Trolling is necessary in terms of the environment. Big fish go for big tackle. Can be as frustrating as fly fishing and as rewarding.
I've never open water spear fished, though I know it has a loyal hard-core following.