Based on the experiences I have seen with others, it looks like CachyOS has more software installed out-of-the-box (compared to EndeavourOS being more minimal). Both look similarly easy to install and offer many different DEs (I think CachyOS has a few more though, but you could manually install others)

I personally use EndeavourOS as I like that it's more minimal and don't really care about the gaming optimisations of CachyOS. It seems pretty neat though, so I might try it out one day if I get a newer computer that would benefit from those bits.