First_Tsurugi06
Video Game Engine of War
I loved the G Gundam one. I remember tuning in every Saturday night on Toonami to watch it just so I could watch the intro (which they always refused to play on weekdays).
And perhaps to add variety to the topic, feel free to also bring up some of your least favorite anime openings as well.
For me, it would have to be Lucky Star's opening. I actually quite like the anime; I find it's slice-of-life atmosphere to be endearing and I sincerely wish they'd renew it for another season or two (not necessarily mainstream, but...) but to start each episode with a cheerleading tribute-whatever dance (I hate cheerleading for one--it's no sport, and there's less to spectate than a pep rally for a charity basketball game involving a middle school staff) literally caused an aching sensation in my ears. I'd go so far as to say it gave me, for the first time, a feeling of emasclation...and it stings.