Not sure where the second to last one and the two in between Bahamut Sin and FF8 are from.

I think the two in the middle are from Crisis Core

Ah ok, google helped confirm that. I'm assuming the second to last one is a personification of the FF12's. I was thinking that the first one just might be a general representation from the earlier games, but it looks like the one from FF3DS.

the gold one is deffinately in Crisis core, dont recall the name though

the gold is Bahamut Fury if i remember correct

The second to last one is Bahamut from FFXII: Revenant Wings. The first one is indeed from FF3DS. You can tell because of the distinctive "hip fins".

Then again, it actually could be FFIV now that I compare them. Hard to tell.

And yet I still yearn for FFI's Bahamut...

The third Bahamut has some crazy ass wings

left to right:
Bahamut FF 1-6 (I think)
Bahamut FF7
Bahamut NEO FF7
Bahamut ZERO FF7
Bahamut Sin/TREMOR FF7 Advent Children
Bahamut FF7 Crisis Core
Bahamut Fury FF7 Crisis Core
GF Bahamut FF8
Bahamut FF9
Aeon Bahamut FF10
Bahamut Wyrm King FF11 Online
Bahamut FF12 Revenant Wings
Bahamut FF13

FF7s the best!

And then XIV Bahamut happened...