I have nothing but good things to say for the Sturmey-Archer 3-speed. It's a damn good hub, and it will stand you in good stead, as will the 5-speed. I've never tried the 2-speed, so I'll avoid any judgements on it, but the idea seems like a good one.

That's not to say the Shimano and SRAM hubs aren't good, but as far as I know, only the SA hubs can be spaced down to 120mm across the locknuts, and that might be a consideration if you have a dedicated singlespeed frame as opposed to a conversion.