Maximum possible value for singular systems, perhaps. But if one is looking for credits first and foremost, then the best would be maximum average value for multiple systems, no? On the whole, it doesn't matter much if you find a single well-paying system if the other fifty didn't offer much.
If so, then that would probably be class F (and perhaps A) stars, with their abundance of WWTCs and ELWs. Plus HMCPTCs, if you're willing to put in the time to look for those too.
How many systems with a red dwarf and 9 icy planets would it take to make up 30m credits, don't bother I've done it already, around 600, and 600 by my jump range makes 39kly. By picking out neutron stars and black holes as I travel I can way more than double the money earned while traveling and scanning and I find a lot of interesting systems, that's not the only one I have found like that. The thing is most of the galaxy is empty, and most of the systems are going to be a single star or two worth around 50k, you only have to find a few systems like the above to make it worth doing.
Fact is I don't filter anything, but I plot my routes trying to end at specific star types. O class, black holes, neutron stars, maybe the occasional B class, I've just done a loop around the galaxy and expect to pick up a billion in exploration rewards, maybe a million in codex rewards, high energy stars also give the opportunity to find biology and lagrange clouds, and Raxxla just might be orbiting that brown dwarf you decided to filter out.
But then I am out here to see what I can find, it would seem, even if your argument is correct, I'm not saying it isn't, I would have to do the maths based on my current data, that filtering out systems based on how much they might be worth isn't the way I want to explore, so in the end it does come down to personal preference as much as anything else.
