Depends what you do, they are good at different things.
ISP is one static IP that stays with you for weeks, and it’s on a server so it’s fast and usually unlimited traffic. That’s why people use it for account management, if you log in to the same account every day from the same IP it looks normal. Also for anything where you move a lot of data through few IPs, there ISP can end up cheaper than residential because you pay per IP, not per GB.
Residential is better when you need many IPs and many locations, scraping, price monitoring, checking results in different cities. And if one IP gets flagged you just get another one, with ISP you are stuck with that subnet until you replace it. Full disclosure, I’m at DataImpulse, we don’t sell ISP at all, only residential and mobile and also dc, so I have no reason to push you either way.