I of course think claws is the best overall alliance to join ; hence why I continue to be an active member of its government.
But no, if you read my other public posts, I recommend other alliances too. Usually NPO, FTW, or CLAWS, since I know them well enough and can point to objective evidence that they are quality alliances. For super large nations who are active I would recommend DBDC too. I note that FTW isn't even allied to CLAWS, but I would still recommend them as one of the best alliances to join.
Depending on what a nation wants ... I have on at least one occasion even recommended (privately) that a nation should consider joining NG or Cobra... I did that when a smallish nation expressed interest in fighting a lot of wars. Joining NG or Cobra is objectively a good way to do that. I have no idea who they're going to fight next. But my guess is that the next war will involve one of those two (or both). And if not the next, then the one after that