Food

I don't think it really matters, if they are cooked well they can both be pretty amazing. Fillet has to be treated differently from sirloin/rump, either sear really quickly on in a very hot pan, then roasted gently, or even better turned into a beef wellington this is Tom Kitchen's recipe its time consuming and there is lots of technique involved but it is amazing!

Rump for roasts and sirloin for steak and chips, deal?
and yes, for beef Wellington, fillet is the only way, that or venison loin.
Somehow I can find very few butchers that sell fillet steak with any decent amount of marbling, they all seem to sell those limp, fat free cuts, which is a bit of a shame really.