Consider the ships ZOI and PVE zones.
Missions have to be very close to the station and offer primarily gunboat missions to contend with PVE zones and even then the Molly related zones take the cake since those fat snubs will be blended up by secondary fire excessively quickly making snubs on par if not your main source of income whilst BC's aren't worth the kill time solo and battleships are nearly not worth shooting since you'll likely deal with the hostile factions stealing your potential income as you waste time shooting a battleship. Same thing with a BC.
At the moment the best zones I've found are:
Poole with its fat easy to hit molly snub spam and gunboats.
Leeds with its abundance of hostile factions to both the GRE and BAF. Preferably fly for GRE since they can keep both the outcasts and CR hostile for the most part iirc.
Dublin with Mollies and the waring GRE and BAF spawns.
Omega 49? If one of the GRE lads who goes there often could explain why because I really don't see the appeal in avoiding interactions just to grind there. But it does have a good spawn rate for gunboats.
So that would leave these ships available for the best PVE contest:
Deimos
Valor
Invincible
Bismarck(?)
Ignoring where these ships can safely grind will have me say literally anything with a lot of secondaries and 4 heavies.
If @Darkstar and @Groshyr could further what I've started with their knowledge on different zones and their ship type spawns that'd be great. Because I feel I'm forgetting Rheinland.
Don't underestimate the income from blending fat snubs. Only for Poole would I consider running Solaris over Secondaries.
Edit: Reason I mention mainly bretonia is because of the fat snubs and fat gunboats. Sometimes the AI dodges and twirls in ways the turret view targeting can't properly hit and that causes you to waste a considerable amount of time on smaller craft. Even Gaian and SCRA gunboats tend to waste time dodging in my experience.