Yeah, I tend to put electronic firing on everything, it reduces recoil and audible perception, both wonderful. Most of my mods revolved around recoil reduction though, as most of my weapons revolve around BF. Recoil, ammo capacity and sound suppression.
As for specific guns, I'm a sucker for Armor Piercing (and recoil comp and sound suppression and burst fire) so I like the Onotari Equalizer for machine pistols (with extended ammo cap.). For Assault Rifles there's a flavor for every need, so I tend to pick whatever I like for looks with the PC.. though tending towards the various -1 AP, 2 RC, and decent ammo capacity (Ares Alpha, HK G12A3z, Sernopal) platforms for general purposes. Haven't ever built a PC with a Battle Rifle but once and I went with the SIG Sauer 574... AP, RC, poor ammo cap. but wasn't so important as the PC wasn't a primary combatant.