I use NostrGram's default "read from all known relays" option and I write to all the top public relays and about 20 paid relays. But NostrGram only shows paid relays in Global and Friends+ connects you to the people you're following *plus* the people they're following, so it's virtually spam free. I'm not sure how much longer public (free) relays will last at the current level of spam they're receiving.