For me, I use Spacebar as a leader key in Neovim, so I think they would conflict.
Does it ever create issues for you if you need to type the backtick in the terminal?
I found that Ctrl-A does a great job: it is conveniently located in relation to other keys that I need to interact with after I activate the prefix, and is in general easy to use.
I also use backtick for my tmux leader key. It doesn't create issues for me in the terminal (but you need to tap it twice when you want a literal backtick). This became natural for me pretty quickly.
Does it ever create issues for you if you need to type the backtick in the terminal?
I found that Ctrl-A does a great job: it is conveniently located in relation to other keys that I need to interact with after I activate the prefix, and is in general easy to use.