ORIGINAL: Centauri
Pffft. The C-5 is just a cargo plane. The A-10 is where its at. It has anti-tank and anti-air capabilities. It looks cool too.
The A-10 would be my last choice when it came to Air-Air Combat, in fact i don't think the A-10 has EVER fired an air to air missile in combat ever lol. If you want tank buster as well as fighter i'd go with the F-16