[Filburt]

I use 0.015" on everything, and I haven't had a problem. Then again, I seem to like an inordinate level of precision, so maybe it's not a practical solution for most people. I like 0.015 because I have a lot of control over how much solder I want in there, and I can use it for both through-hole and SMD work, so it's convenient in that sense.

 

[threepointone]

I've got a bit of a solder collection with me, almost all stuff by kester, multicore, and a bit of rat shack; rma/no-clean; 60/40, 63/37, 62/36/2; pretty much every size, including some exotic .010" solder I found. I admit, I've done a whole lot less soldering than I have solder, since I've "inherited" most of my solder. In general, 62/36/2 (silver bearing solder) is absolutely the most annoying stuff to work with. Haven't noticed much of a difference between no-clean and rma, or among brands (except that the burning flux smells kinda different. . .multicore smells kinda nasty IMO, but try not to smell it since it's probably bad for you). Naturally, the larger gauges work better for THM (about .020"-0.30" or so). Personally I tend toward the smaller gauges, about .020", for THM work, and about .030" when I'm doing the panel mount stuff. 0.015" is great for pretty much anything surface mount, while .010" seems to be only useful for a few surface mount applications--it's rather finicky because it puts so little solder at once, and it bends way too easily.

In short, I'll use anything but silver bearing solder.

 

[mono]

"IF" I could only choose one diameter for everything it would be 0.025. That's smaller than required for through-hole, and about as big as you'd tolerate for SMD. So it would be a compromise, ideally you'd have more than one spool of solder.