Stick with what colours you feel confident in. The plug action is more important than colour and I think size as well. When fishing really deep, sometimes it's nice to throw the Tubbys down to allow you to slow down a little to redice the rigger cable angle. Or when the tides are really ripping, you can keep your rigger angles a little less extreme and still be confident your plugs are dancing nicely. I'd suggest grabbing some glow patterns - 600, 602, 632, 639, 700 - when the waters are a little murky in the spring. The UV plugs are great - the 645 or Herring Aide seems like a great one for the SOG when the waters are really clear, but any colour that catches your eye - greens like that 646 you posted will perform well. Also, can't go wrong with the classic pearlescent bodies like the 500, 158, or most plugs you'll find in the bargain bin. Don't walk past a bargain bin of plugs... Depending on where you're fishing you might find the size of the plug makes a big difference, but I've found that a good plug usually works no matter what bait is around.