Alright, I have to give this long preamble because otherwise people will get mad at me for leading your astray. So, let me be clear, I am by no means advocating that you allow the pursuit of money to suck the fun out of eve. Instead, I’m trying to say that, if you’re going to isk grind, you should make sure that you’re not toiling away for garbage money.
So, yes, you should prioritize having fun -whatever that means for you. Some people hate isk grinding, and try to avoid it as much as possible. If you fit into this category, you should probably do the same. For others, “the grind” is what they enjoy. They enjoy mining, fc’ing incursion fleets, multiboxing the abyss, or whatnot. So, for them, there is nothing wrong with spending your play sessions doing such things. For others still, they might like a certain amount of grinding, but find doing too much of it to be draining. So, the key here is to figure out what is fun for you, and not to overdo it because you think you have to (you don’t). Moreover, don’t let anyone else tell you that you’re playing the game wrong, if the way you’re playing brings you enjoyment.
Second, don’t turn eve into a job (unless you enjoy treating it like a job). Many people think they need a lot of money to PvP or to be competitive -you don’t. Don’t get me wrong, having more money does provide an advantage, but it is not a prerequisite for fun or for winning fights. So, don’t burn yourself out chasing money you don’t actually need.
Third, if you are the type of person that hates isk grinding, and want to do as little of it as possible, you should either (1) try to make money through PvP or (2) raise your isk efficiency to a respectable level in order to minimize your grinding. In other words, don’t waste your time toiling away for garbage money. Others might disagree with me, but I’m of the opinion that if you make less that 100mil isk/hour, you’re making garbage money, and should be actively working towards improving your isk efficiency. I mean, there are just way too many ways that you can make 100mil+ isk/hour without too much risk, investment, or effort. So, to me, that’s like the floor.
Whether or not you want actively work towards making more than that is up to you, and will depend on a zillion different factors such as your spending habits, your tolerance for grinding, and whether your prefer a greater isk efficiency or less effort/attention. However, I don’t think it’s unreasonable to try to shoot for around the 250mil isk/hr range. It’s not terribly difficult to achieve, and that kind of money makes life easy (i.e. it would only take 5-6 hours to plex your account, and it makes subcaps quite affordable).
So, in order to answer your question, I consider 100-250mil isk an hour to be a “good” income.
Hopefully, I answered your question (and that all made sense).