Slayer and BTB are the only gametypes you'll always find a match in (5-10 minutes). Most other gametypes have a good amount of players in the afternoon (for me: Belgium).
It's kinda funny, I took a long break of H4 but last month I started playing again and I'm still trying to get most commendations, but that's really hard if nobody plays CTF or Flood anymore. I already completed the player and weapon mastery, vehicle destroyer is 93% but I'm never gonna get enough mongoose destroyed! XD
Unless.... someone wants to help me? :) X360 only.