I think one of the most customizable ones is khatru, it have a lot of policies already made for you to use and you can also create your ones, is not the most noob friendly one since you need to write a little bit of go code (~50 lines of code) which is fairly short. But you get a tailored relay with a little memory foot print 👌 khatru.nostr.technology 

 Just had a look now and it feels amazing but a bit too much for a non dev like me