What seeds should i choose?

I give importance to yield, because i can do only 1 plant. So i think that i will go for an auto ultimate with lst, i saw some diaries and seems GOD.

Since you have a small space, the strain variety that will save you the most time is Feminized Sativa dominant seeds. This will endure a short time in the vegetative phase and a good stretch during flower, because of the sativa dominance. The Indica part will ensure nice colas. Just make sure to top and LST in vegetative phase.

Depends what you're after. Yield, potency, flavour, colour, size, what are you after? Most autos will fit in your tent, you need to works out your tastes. You're the one who gets the final product :) my mouth waters over some of the flavours out there. Good luck, have fun choosing!