It really all depends on this situation and what class/guntype I am useing. I will go ahead and list my current setup's: For my assault rifle run'n'gun class I use C4/Portable radar-For my Knife/submachine gun runner I use portable /Semtex/Stun-For my sniper class I use Claymore/Portable radar. And my choises tend to change for the rest of my classes, I like to use the throwing knife and tactical insertion much of the time.

I have been running semtex/concussion on most classes. I do have a C4/Portable Radar for SnD and Demo. Had my fun with Boucing Betty during first prestige. Seems like it isn't as effective as it once was.

Semtex, Claymore or C4 all work and the only way to go for the tactical is Portable Radar.