If you want to plant bombs you'll definitely want marathon pro. Marathon is good, marathon pro is great; it keeps you running for as long as you need and really helps you get to the bomb site quick. For your first perk it depends on how good the team your playing with is, if you're playing on a bad team or with randoms the other team will probably have a lot of kill streaks so use ghost, but if you're confident that the team you're playing with is decent you could really use any other perk besides scavenger. (You can of course switch to a ghost class if one guy on the other team is 4-0 and probably has a UAV and could get more). My last bit of advice for a bomb planter is use a silencer... when rushing if you're firing an unsilenced weapon 10 feet from the bomb it will probably attract a few enemies.
sorry about the wall of text but here's one of my classes: MPL silenced any pistol
ghost pro (randoms)/ flak jacket pro (party) steady aim pro marathon pro
yes this guy ^ definitely knows what he's talking about. I've seen some of his videos and he has good classes in that video as well. I forgot to mention what he said that jammer is very good for planting/ rushing as well because it allows you to not worry about the possible claymores/ motion sensors around the bomb