I have to agree about the NS-7. It looks better on paper, but I still prefer the Cyclone
It is hard to recommend weapons due to differing play styles.
These are my preferences, but remember the default guns are pretty good.
Engineer - AC-X11 for medium and Warden for distance.
Light Assault - Cyclone for close and Warden for distance.
Infil - Cyclone for close and Longshot for distance (some prefer the RailJack)
Medic - Carnage
Heavy assault - Anchor