Which of these PS3 exclusives should I get first?

Get whatever game you want. Tekken Tag is not exclusive, but if you are into the series, then get it. Most PS exclusives are pretty cheap. You could probably pick most of the titles up for $30 or less.

Ratchet and Clank ACiT, Infamous, and Ni No Kuni of those options. Then get Little Big Planet and Dark Souls.

You forgot the resistance series

^This, and where's Killzone, Heavy Rain, Beyond 2 Souls and The Last Of Us??

Should throw in Jak and Daxter games.

I prefer Tekken Tag Tournament 2 off that list, great fighting game with lots of stuff to unlock and great customization options.

demon souls

i would go with Ni No Kuni i also recomend playstation All Stars, it's a really fun co op game

Every PS3 owner should play a God of War game, I think. Some gamers bought their consoles solely to play as Kratos. = )

On the other hand, you wrote about "freedom of choice", so you should also play Infamous.

i would not buy most of those games on that list. But infamous was fun..... when it came out. it's kind of dated now.

for this list ni no kuni god of war saga demons souls infamous

If you consider the "buck per hour" rate these games offer, I'd say the God of War Saga and Ni no Kuni are strong choices.