which to focus on?

I'm trying to decide which toons to do the whole Alpha slot thing on. I've unlocked it on all of my lvl 50's, but it's slotted only on two so far.

I consider my main to be my fire/SS tank. My second guy is a fire/EM blaster. But from the rest of my toons, I can't seem to decide on a third...or fourth, etc. So I come asking...if you had to pick one for your weekly TF team, which of the following would you rather have?

Ill/FF controller
Kin/Rad def
Fire/rad controller
DM/SR scrapper
BS/regen scrapper

All of them are good in their own ways, but I want to work on one that would be most desired by teams. I assume most would pick one of the buffer classes, so I guess I'm asking which buffs/debuffs people tend to prefer the most.

I also have a second similar question. I want to move one of my vils to hero side, and again I want it to be the one people will prefer teaming with. It's either a spines/nin stalker or a Night Widow. The playstyles are very similar, so which one would you pick?

Kin def - tough to beat SB/FS.

NW - team buffs are good.

A Kin/Rad Defender or a Fire/Rad Controller would both be very handy on most TFs. The Ill/FF would also be nice but FF just offers protection while Kin or Rad boost kill speed so as long as people aren't dying often most teams would probably prefer to steamroll faster.

As far as the villains go, a Widow is always handy (be sure to take the Leadership pool as well for double buffs). The Stalker may play the same, but he doesn't make everyone around him harder to hit and up their damage like a Widow does.

Oops, I just realized I posted this in the blaster forum instead of general AT's. But thanks for the replies so far!