On thing about back buttering is that you dont easily end up with
empty pockets of air under the tile. I sort of do a little of both
myself.

I lay the thinset on the floor, and then on each tile placed I put a
small amount of thinset in the center. This sort of makes the problem
of air being trapped under the tile go away.

On thing is make sure that you subfloor is strong. Using a good
thinset
is the next best investment.