The legions I'm most familiar with:
Death Guard - it's either infantry, or super heavy tanks. There is no in between. March it all right up the board.
Emperor's Children - 10 man squads mostly, take all the options and upgrades you can, get a nice elite unit (terminators or some other goodies) and have them leading the charge. If you're looking at post-heresy then things get a lot more flexible, as the legion was on the verge of tearing itself apart on search of experience.
Blood Angels - What's this 'staying still' you speak of? Plenty of jump packs, transports and fliers. Lighting fast assault units are what they're good at.
Alpha Legion - the ultimate in pure, un-cut, absolute f**kery. Use all their special abilities as much as possible - steal units, screw up reserves and take out as much as you can before it even touches the board

. Also tend toward deep strike yourself and high powered attack units.