I've tried both, and even the time I spend with the charge backs and "I changed my mind and want a refund" aren't worth my time dealing with. It's just boring hassle.

I definitely agree, there's a balance between making easy ad money, and satisfying users. That's the hard bit - making the advertising useful enough, unobtrusive enough, but effective.

A lot of it perhaps depends on what sort of person you are. Making money from advertising is basically a numbers game, which you can just optimize iteratively. Selling subscriptions involves feelings, random users, and all those fuzzy things that I personally find a lot harder. I'm not a salesman and never have been. I don't like trying to charge people for something I'd never pay for.

OTOH, I would, and have paid for advertising, I have used websites that carry advertising obviously, so I'm just a lot more comfortable with that whole ecosystem. I can put myself in the position of all parties.