Though there are considerations that would convince me to try other things, a wet or streamer, in attractor colors, would be my choice.
One of the major considerations is ‘when’. What time of year is it, also, what time of day. If I’m hitting a local stream late May, early June, after 4pm or so, even without a single bug in the air or rise, i’m going to a large 12 or 14 para-adams, because any time now, the isos are due up, which will cause a feeding frenzy until it’s too dark to see your fly on the water. This time of year, on the same water, it’s well worth trying a caddis pupa or emerger in the film, to address the sporadic hatches that occur from the end of summer cooldown until the first frost. This fish, by now, have learned not to miss these opportunities, and will readily take a caddis emerger any time of day. After we’ve gotten a few good frosts, I can pretty much leave my dries at home. Some midges will be coming off, but if you want to fish that hatch, you’re better served fishing a larva or pupa.
Another major consideration would be the habits of what “should” be hatching. During the sulphur season, but before the evening hatch, I’ll try a flashback PT, especially if the duns aren’t popping off yet and the trout arent rising to the other bugs. Usually means they’re already keying on the sulphurs, but those sulphurs are still subsurface.
That said, without any prior knowledge of the location, hatches, or seasons, a small bucktail streamer that incorporates and combination of white, olive, brown, black, and red would be my choice. I’d start smaller, maybe a #10 or so, and once I got into a fish or two, jump up to a 6 or even a 4 to try to tempt larger fish.
I dont like spending my fishing time sitting on the banks. I prefer to be observant while I’ve gota fly in the water. If a hatch starts to occur, its a simple matter to change things up to address it.