All noseguns benefit more from magazine size upgrades, except the high capacity ones which benefit more from reload speed (but it’s a small gain and a waste of certs early on).
Zoom is usually not recommended on anti-air noseguns, as it makes the ESF less responsive.
Air-to-Air
Stock (Needler, Mustang, Saron): Best all-around for A2A.
Rotary (M18 Rotary, Vortek, Maelstrom): Niche for A2A. Better DPS but lots of drawbacks. Good for jumping ESFs from behind, worse for 1v1 hover fights and killing large aircraft.
High Capacity (Locust, Kestrel, Antares): Niche variation of stock noseguns. Avoid if you’re new.
Air-to-Infantry
Banshee/AH: Good vs. infantry, mediocre against ESFs, bad against everything else.
PPA: Decent vs. infantry (a bit better than rocketpods), bad against everything else.