I play a TI and confirm on most of the positive comments you got.
Still it is untrue that one synth can sound like all the others. The TI is covering a very wide area from warm vintagesounds to cold industrial sounds, but of course it has its own basic sonic character like anything else. It does not sound like a Moog, an Arp, a Korg Polysix or whatever. So despite liking the Access TI very much, I still appreciate the sounds of other synths as well.
Arturia did some very well modelled software VA synths coming a bit closer to some vintage origninals than I can with my Access. I can't tell anything about Origin, because I'm still missing signigficant mp3 demos. But it will have its own character as well.
So the first thing you should asnwer yourself is what kind of music you want to do and what kind of synth sound might fit that music best. And instead of just reading specs and even hearing demos it's still the best to walk into a store and check sounds with headphones on.If possible, don't only check the presets (they are often poor to middle class) but tweak a bit yourself to get a first impression...