Quickly for you.
Basically there is UC and everything else.
UC stands for Universal Century. There there is AC from Turn A Gundam which means Another Century (Suppose to be the ending to all Gundam series) There is another AC which stands for After Colony from Gundam wing. There is also CE for Cosmic Era that are for Seed and it's sequels.
Now the hardcore Gundam fans (Like myself) feel that Only UC and AC from Turn A are worth thinking about when you wanna set yourself in a timeline. Everything else are stand alone shows with the Gundam Name on it. However due to some scenes in Turn A we were lead to believe that every gundam series is set in the "same" timeline just widely stretched in time. (If you don't know what I'm talking about go watch TURN A now!!)
Now for the best gundam Pilot.
I'd really have to go with either Char or Amuro. Kira comes really close in second place. It's all due to their Newtypes powers. Even if Kira is a coordinator with awesome reflexes and physical abilites you just can't mess with the abilites of Newtypes.
Best Gundam (ZOMG if only you hadn't specified gundams).
If we are going with raw power and greatness
I'd have to go with the RX-78GP02A Gundam "Physalis"
Seriously Nukes + Gundam = Win
My personnal favourites are all non gundams though.
MSN-04 Sazabi
OZ-00MS2B Tallgeese III
MS-07B-3 Gouf Custom
Geez I'm such a Gundam Geek.