I love being a field op... And raining destruction down from on high.
That being said, if I'm playing as a strogg, I usually roll as the medic class (can't remember it's name.)
I've been digging on non ranked, no xp reset servers. And play whatever class is needed at the time. Makes me feel like I'm getting something for my time. Because I could give half a flying fuck about the Ranked XP system.