Though if you want to watch ZZ, that's fine, just don't go in expecting another Zeta.
In that case save Unicorn and Gundam 00 for last because once you've seen these two you will not be able to watch the older shows...
ZZ
0080
0083
8th MS Team
Victory
X
Those are the only ones left. I left out Wing and SEED/Destiny since they are probably not your type. SEED/Destiny is just the modern angst filled version of 0079/Zeta/ZZ anyway.