There are too many hubs that are basically the same. As long as you stay away from cheap hubs, Suzue, you really can't go wrong, unless you install something incorrectly. Choose what type of bearings you want, cartridge or loose ball, and just pick the one you like the best. Or you could search the other 5,000 threads on this topic and read to your hearts content.
phil wood, offhand, is probably the highest end brand that makes a hub with one side with stepped lockring threads and the other without (for singlespeed).
that said, however, you can use any double-sided track hub, because freewheels work just fine on track threads. they end up engaging with fewer threads than a purely single speed hub, but it's a non-issue. you also have the advantage of being able to do two fixed cogs, should you end up not wanting a freewheel at all. if you aren't doing a ton of bad weather riding, this opens up the possibility of using dura ace hubs, etc.
^not ENTIRELY true. I always figure that if someone KNOWS they're gonna be running an SS on a conversion, the SS side could be helpful ie:more room for spacers to get correct chainline. I guess.
yeah, who knows. if you need the ability to push out your rear chainline in order to accommodate a less-than-ideal crank/bb setup for ss, then you're going to be hosed when you flip over to the track side, where you don't really have similar room for spacers and the like.