Well there are alot of series, both short and long, that are in the U.C. Timeline.
Mobile Suit Gundam, Zeta Gundam, Double Zeta, 0080 War in the Pocket, 0083 Stardust Memory, 08th MS Team, Char's Counter Attack, Igloo, Formula 91, Victory, and i THINK Turn A belong on the Universal Century time line.
Then you got out of nowhere stuff like G Gundam, Gundam Wing, Gundam X,Gundam Unicorn...
Then there is Gundam SEED, SEED Destiny, and Stargazers..
and the latest is Gundam 00 that had recently finished it's first season.
All i can suggest is good luck! And give whatever one you like a shot as well as disregard both good and bad hype. SEED and SEED Destiny are much hated in the USA but Japan fucking LOVES it.