I like the idea of an included adblocker but for me with maybe 500-600 own rules it is too blunt of an instrument. Is it still a combo of ublock, umatrix and ghostery one should use or is there any benefit in letting the built handle some generic stuff?
Welcome to Opera's forums @Rfa2!
AFAIK there are some blocking list that AdBlockers and Opera AdBlock uses to block ads, the only difference is that with extensions or system blocking apps you are able to block manually some ads or elements and that cannot be done in Opera, at least yet.
There is an option to add a custom list, but you'll need an app to block the new ads and then export and import the list.
The extensions that you mention are more complete if Opera AdBlocker is not enough for you browsing use.
Another thing is how optimized is built in adblocker and extensions, the battery could be drained faster with a lot of extension for blocking ads.
In my case I use AdGuard and Popup Blocker and some UserScripts too.
A Hosts File it's a helper too.
I have returned to uBlock Origin from the built-in ad blocker again until Opera’s ad blocker matures to the point we no longer need extensions. uBlock Origin should be more than plenty for ad blocking. It is possibly the most lightweight extension there is currently. The additional CPU cycles by ad block extensions do not matter for modern PCs.
Combining multiple ad blockers is generally not a good idea if that is what you meant by ‘lettering the built handle some generic stuff’.