The shosho backend seems to be the most popular. Why? Because it just works! and it's free!

nostr:nprofile1qqsgthcq5tm2jxz9x4xg6tvlh26qq2actdpztwh2kc86lvjc03gr36spzamhxue69uhhyetvv9ujuurjd9kkzmpwdejhgtcpz4mhxue69uhhyetvv9ujuerpd46hxtnfduhsz9nhwden5te0dehhxarjv4kxjar9wvhx7un89umukq8g is winning!