Not sure if best but I’m using these:

https://nostrcheck.me/media/00000000827ffaa94bfea288c3dfce4422c794fbb96625b6b31e9049f729d700/7248db1b866430103ff0411291df1be4815b8f902402f7096b85f5c43ba47e48.webp

There are lists of relays with connection stat's at:

relays.xport.top

nostr.watch

nostr.info