Sexy Cakes' estimations are pretty close in my experience. The real differences between Incursions (i'mguessing we're mainly talking high sec incursions) and Sov Null pve (anomalies, belt ratting and complexes) don't necessarily have to do with income considerations. Other considerations are convenience/wait time, safety and your own mood/preferences.

I prefer null sec pve (my null sec toons live in the Delve/Querious region) because I can do it solo and/or in a small group (i've got one main 'carebearing partner' and sometimes we go help corp/alliance mates with difficult sites). I like high sec incursions a lot, but sometimes having to wait to get into a fleet is annoying (and costly) and not being able to start/stop when I want is also annoying.

The upside to high sec incursions is the safety, you have CONCORD protection + a squad of logistics in case a gank squad wants to make a try on you while you are in a site. In null you have local and intel channels but you can do everything right and still get caught. Get caught by a solo guy and you have a chance, get caught by a guy with a gang nearby and you are replacing a ship lol. Wormholes are the main menace in null sec now that the chance of hot dropping has diminished (but not gone away) due to the jump drive changes.

High Incursions are steady isk and nothing about it's rewards scheme is chance based. Null sec pve is a mix of static rewards (anomalies are the best for this) and chance based rewards (loot drops from commander/overseer npcs in complexes and sometimes in anomalies). You can make a killing in null sec pve one day (getting x type loot and pirate ship BPCs from one loot drop) and barely skrimp by the next (getting nothing but npc bountes and no seeing so much as a 'commander' spawn in an anomaly).


So it depends on what you want: steady income and safety but with sometimes having to endure a wait list) or less steady (sometimes more, some times less) isk while having to dodge 'ceptor gangs and wormhole raiders but with having more personal control over your pve play time (also dependent on what kind of null organization you join, some null groups have 'cta's' that require you to stopp ratting, I get past this with alts lol).

Also to note that HQ incursions require you to be in a fleet of ~40 and all on comms. While this doesn't affect income not everyone likes being on comms with randos for many hours on end.

Ishtar pulls in 60 mil an hour.

Pirate battleships pull in about 100-120 mil an hour.

Carriers pull in 100-150 an hour.

With any sort of decent LP conversion incursions are better and vastly safer.