Personally, I wanted to bring some fresh options to the game rather than the current three guns: Bizon, P90 and Negev. All other guns were not viable due to low counts of ammo or less knockback.
My current ideas were raising the m4a1 (Both silenced and normal) and the AK-47 to 50 bullets minimum. These both being higher knockback guns would do better with defense than most other guns.
The MP5 would be great with 50 bullets compared to 30, and would be an alternative to buying Negevs with its fast fire rate. The UMP or MP7 would also be an option, although I'd recommend only one extra SMG since there are already two in the current meta.
Also adding an extra 12 bullets to the Nova for boosting EXTREME DEFENSE