I'd be a Heavy Bolter-totting tactical marine. As my sergeant and half of the squad jump in a razorback to go burninate things, i take aim and start mowing down greenskins like i was trimming a hedge. My squadmates would die first, The Emperor graciously allocating the first 4 wounds to them.
then, as the orks inevitably approach, i'd laugh, because they were all about to be killed by a heavy bolter marine that remembered to put on an appropriately oversized bayonet. Brother Rambo FTW.