Question about guitar pickups (humbuckers, single coil, active and pive)?

As far as I know (what little that is), humbuckers can be either active or pive while single coils can only be pive. I could be wrong, but who knows. Anyway, what is the best combination to have on your guitar if you want to go from either clic or modern metal to something soft and sweet that still has a good, unblemished tone to it? I've been eying one guitar that has three "Mega'Tron" humbuckers and you can use any combination of them at one time (the "Stump-o-matic"). I have also been looking at a guitar that has the HSH formation (humbucker, single, humbucker). What's going on there? Is the single coil used for more clean tones? Don't really know... Anyway, I've been hearing that some of the most popular humbuckers are Seymour Duncans (don't know what type, exactly) and EMG's (81 and 85). Any thoughts and opinions on this, or if the Mega'Tron ones are any good?