I whitelist the websites that I use regularly, but if they use ads that:
1. obstruct parts of the website or automatically redirect to something else making navigation hard
2. automatically play sounds - I'm not too bothered by small videos
3. are flashing heavily/ are very distracting making reading the website a horrible experience
4. slow down website loading (not just by a bit, but very noticeably so) or slow down my PC to a crawl
then I activate adblock again, but I do try to give them another chance like every month