Obviously this is very much a matter of personal preference, but I feel that the water itself may make one method better than the other.
Some rivers, like the Thompson , are wide and have large pools with a bottom of large boulders.The spring freshet carves many trenches behind these boulders and each of them can be an ideal lie for a steelhead. These lies can be almost anywhere in the river. Thus for the Thompson I believe that a lure which swings across stream is likely to be exposed to more fish than one which drifts straight downstream. Such waters I think dictate the use of drift lures.
Other rivers like the Vedder have a narrow central channel of fast water and distinct seams occur along the edges due to shorline influences. The lies in this type of water are usually along the seam which is formed near the shore. Ideally more fish will see the lure if it travels strigh downstream along the seam. Float fishing is the easiest way to make your lure or bait travel in theis seam at the proper depth.
So for this type of water I prefer float fishing.
When and how do you make the choice between float and drift.