Its really going to depend on 1) what your willing to pay and 2) what your needs are.
The GNU carbon credit is a very entry level board, im pretty sure it has an extruded base. If you just want a board to ride, have fun on, and dont plan to really take great care of, thats the board for you. for example, not waxing as often as you should. Your unwaxed extruded base will slide better than your unwaxed sintered base.
The banana is going to bump up in quality for the CC series.
Both lib tech and gnu have different models for different things, gnu having the entry level stuff the lib does not have. Gnu does also have the high quality gear, but theyr boards for the masses offering kids boards, womens boards, and entrylevel boards as well as the advanced stuff. Lib is mainly hardcare shit
For all mountain, I ride a 2010 Lib T.Rice 153 with btx. awesome board and love it. Never have to sharpen edges. Ive sharpened my 07 Trice with mtx once.... still ride ice like its no big thing.
If your a park monkey, get the Lib box scratcher or the gnu park pickle.
get back to us on your needs, IE how much you wanna spend, area youll mostly ride, stuff like that and we will be able to help you more.
If you liked riding that carbon credit....the mervin line just gets better from there