Amethyst use the outbox model, which I believe is the reason you can set specific relays to handle your private/public inbox, DMs, private and local relays and general relays. Amethyst seems to capture posts and comments I can't see with any other client. Just go with what Vitor recommends and add to it if you want. Problem is not everyone uses an Android phone. I want to try and like other clients, but honestly, and I don't want to discourage development in any way, but Amethyst is what I use unless I'm just trying something else out.
Where can I find @Vitor Pamplona's recommendations? And I agree, I have the smoothest time on Amethyst overall. Primal is my backup and the one I recommend to most newbie friends since it spans across Android/iPhone/Desktop, so I'm with you on that struggle; I hope all of these clients play better together soon
In Amethyst, settings > relays, there are a couple of recommendations for Search and DMs. But if you go to the General Relay section and tap "Default", you can use some of those for your public/private inbox, public outbox, etc... Some that are really good, that can be used for DM, private/public inbox/outbox that have come up in discussions (I don't remember where) have been: wss://nostr.mom wss://nos.lol wss://relay.0xchat.com wss://nostr.bitcoiner.social The others in your General defaults list are probably really good options as well. These will definitely get you in the mainstream, from my experience. Others may want to chime in here...