well, it's a pretty personal question. everybody's got different preferences. and budget is another factor. but here's my two cents:
Headset - i like Chris King headsets. they're pricey, but i think they're worth it.
Handlebar - i love the Salsa Moto Ace Bell Lap bars. i wish i had them on my road bike too, really.
Stem - meh. i usually just buy the cheapest thing in whatever length and rise i'm looking for.
Bar Tape - Cinelli cork. is there anything else?
Saddle - whatever fits your sit bones.
Seat Post - lots of folks like Thompson posts, i just buy whatever's cheapest.
Front Derailluer - i use a Centaur double, but how much difference is there in FDs, really?
Rear Derailluer - i use an old XTR 952. but, again, it's all about personal preference.
Shifters - most people seem to use bar ends. i use Centaur brifters. personal preference, again.
Crankset - i like my FSA, but i think pretty much any double would do.
Bottom Bracket - to match the crank.
Cassette - depends on use. i'm running a 12-25, but many folks use stuff with lower gearing.
Chain - meh. i just buy whatever mid-price chain is in stock at the lbs.
Brakes - don't ask me. i went disc. and i'm using some NOS Onzas on my next build.
Cross Levers - i don't use them.
Levers - see shifters.
Fork - no opinion.
Wheelset - i like custom builds, based on use. no opinion.
Tires - depends on riding conditions. i run Continental Twisters.