Well this new demo does not have the largest weapon selection but i can tell you this regarding v0.6 demo.
Ignore the katana, doesnt deal enough damage, breaks if used too much and no area of attack, meaning if you get swarmed ya fucked.
Ignore vector submachine gun, it only deals high damage because you can empty an entire clip in 3 seconds. Not worth it.
Also ignore Mossberg shotgun, while it was buffed and is a viable weapon now, on v0.6 it sucks, deals too little damage up close and you need to pump the weapon so you lose alot of time.
Anything else has passable grade.
Only weapons you should really watch out for are the AK 47, for its consistent and reliable damage, be it up close or afar, and the Spas shotgun, that deals greater damage than the Mossberg, doesnt need to be pumped so you can burst enemies down and its high ammo count.
Also grenade launcher is only ever good if you have an ammo box nearby or for the warehouse fight since you can use it alongside spas to deal with groups of Z fast and to speed up the girls carrying the boxes.