MOH:AA was my drug of choice for about 10-20 hours a week for about 6 months.
I love that game.  Both MP and SP.
The Spearhead expansion is a lot of fun too.  But the SP campaign is very short.
For the past year, it's been all BF 1942 all the time.
I think MOH is a little better when it comes to infantry combat, but BF has so much more variety with the different classes and all the vehicles you can drive.  Ships, subs, tanks, jeeps, APC's, fighter planes, bombers, mobile artillery.
For awhile, all I was playing was the DC mod.  But I was NOT happy with the changes they made in DC 0.39.  So I've gone back to playing standard BF at least until DC 0.4 is released.
Definitely download the BF multiplayer demo and check it out.  It's a fully playable version with one map (Wake Island).  Wake is actually still one of my favorite maps.  The demo is free, and kept me occupied for hours and hours before the full game was released.  I got more play time out of that demo than any other demo ever.  But beware, BF is even more addicting than MOH.