Understood
If you are well and truly locked into playing GW, and have a choice between Marines or Bugs, I would certainly recommend the Marines. And as a new player, I would recommend doing a lot of the boring stuff: 10-man Tactical squads with Flamer and Missile launcher repeated ad nauseum throws out a helluva lot of firepower. Back it up with a Dreadnought, and your oponnent looks like swiss cheese.
When I decided that i wanted to get back into 40K because it seemed to be the only game going on, I decided to field two Tactical Squads with plasma gun and rocket launcher backed up by a dreadnought with twin lascannons and a missile launcher as my basic tactical element. I don't have my noted in front of me, but I think I did this three times and supported it with a Land raider and an officer. Of course, I decided that i really hate 40K and I don't get out much anymore as a result.
Don't take us old-timers grumbling about GW that seriously. It is a great introduction to the hobby. Just don't discount other stuff later on because you believe GW is the ebst