Now I'm not sure if you referring to custom sleeves or the stock tips that come with the SM3s. You can get Shure triple flange tips and cut them off to become biflanges like the grey ones which come stock. The other sleeves which come standard are the Comply tips, so those should be easy to obtain as well. Or you could use Shure grey flex tips or Sony hybrids. If you're talking about the customs then I would imagine that any sleeve such as the UM56 or ACS custom would work just fine for you. YMMV of course, but in general I would say that there isn't really a "best" but merely what is more comfortable to you material wise and the quality of the fit you get from