Anyone who uses Commando has absolutely no skill whatsoever in my book. That is the cheapest perk in CoD history. I would rather be last standed than killed by that perk.
As far as most used classes go, I snipe on 80% of the maps nowadays so I use the Intervention mostly, but the Barrett if I'm sucking with the intervention.
Intervention w/ FMJ
Semtex/Stun
Sleight of Hand Pro (Because I like to quick scope like the kids do these days)
Stopping Power Pro (Or Cold Blooded Pro if I'm playing hardcore)
Ninja pro (The only logical choice for a green perk)
If I'm not using a sniper then I'm most likely rushing with a UMP with the typical rush setup. I prefer Stopping Power on it rather than Lightweight just because I can tell a noticeable different between the two perks on the UMP.