spacemacs is for vim users. No one who doesn’t use evil mode uses it. Also most people who use evil-mode probably use spacemacs.

Emacs keybindings are burned into my brain at this point, but if I had to do it again, I would probably go with spacemacs. I think modal editing is probably superior.

I don't use evil-mode (anymore), but I still use Spacemacs. I'm too lazy to configure everything myself (language modes, Helm, Projectile, Magit, etc) so I use Spacemacs as a starting point and load a bunch of extra ELisp on top.

I'd recommend Spacemacs (even if you're not using evil) if you're new to Emacs and want to see how different and powerful a fully customized Emacs is when compared to the bare-bones experience of stock Emacs.

I’ve never used it, but I use prelude. Is spacemacs better?

Almost certainly. The "point" is that vim has the better controls and emacs has better everything else.