Just go for GamezBD. Despite I don't rly like it, there is simply no better alternatives.
It has somewhat working anticheat, it has largest playerbase compared out of all private servers, it has most up to date version out of all private servers. Also it's oldest private server that I know, have no idea when it was created, but I definitely was playing on it in 2017.
I haven't played EvolutionBDO myself(because they are the only private server I've ever seen that only compatible with windows10), but
[Only registered and activated users can see links. Click Here To Register...]is some interesting info about EvolutionBDO that was posted on this forum recently.
Other servers might have higher rates than those two, but generally they are not worth playing due to being outdated, buggy, and missing a lot of features.
Btw, nothing stops you from downloading multiple clients and trying/comparing them out yourself.
Oh, forgot to mention another interesting option: Retail test server. Kind of sandbox server to try out newest content that not yet released on other regions.
You basically start as lvl60 character with tons of skillpoints and ways to get infinite amount of money/enhance materials/endgame gear/best mounts/etc.
As a downside(or not?) it has absolutely no cash shop, so you are missing out a lot of nice outfits. Also sometimes it's getting wiped.
iirc it requires you to have lvl56+ character on one of the retail server to register on test. If you want, I can give you test server account though.