Gundams in OO are more original when it comes to mech design because they got rid of the old roman soldier-like look. You know, the traditional V antennaes; Skirts (yes, Skirts); and the leg designs.
G gundam on the other hand is probably, for a better word, jumped-the-shark concept because of its surrealism. It's like Dragon ball made into a mecha series.
When it comes to design, I hate gundams with wings. No offense to Wing zero fans or Freedom fans, I find the wings very redundant in a mecha design. All you need is a big-ass backpack and you're done! And I love the sweet bulky gundam designs that of the Avalanche Exia, or the ever sweet Heavy arms custom and the ever classic GPO2A.
And puhleeze! Turn A gundam? That's shits better off the toilet. And the things I hate about SEED Destiny is the Akatsuki gundam, holy hell! That gold plating is giving me seizures! Goddammit! Its color pretty much overshadowed its design. And the walking abomination known as the Destiny Gundam, I mean what's the difference? I like Astray Blue frame second L better than this piece of dogshit.