I don't have a preference really. I started with the 285's because I bought the wheels used and that's what came on them. Then when they wore out, I swapped to 305's. I loved the look, but it rubbed like crazy and my rear fenders are rolled flat. Then my wife drove over a piece of metal and destroyed one tire so I replaced the set w/ 295's. It rubs much less, but doesn't look quite as good as the 305. They all ride about the same since there's a lot of sidewall.
If your offset in the rear is +47, just get the 305. They'll help fill out the wheel well better. Mine was a 10.5" rim at +25. And yes, my FX is lowered on BC coilovers. Ride height is less than one finger gap in rear and front.