Well, IMHO, 1.3 is nice and quirky because of its orange and blue-ness!
But for anything other than games use, I'd not bother with any of the 2.x series when 3.1 offers much more and works with the majority of older Amiga hardware.
And for an expanded Amiga with graphics card, it's pointless using anything less than 3.1...
But each to their own, depends on what you use your Amiga for at the end of the day - the important thing is that it is used and you enjoy it!
- Ali