A chain tensioner is a lot simpler to set up and maintain. Any other way of tensioning the chain, like an EBB or magic gear, usually requires regular maintenance to ensure the chain remains engaged.
I’d you can, get one that allows you tension the chain in both planes, so both inwardly and outwardly. I found the former was better for sscx riding as more teeth in the cog were engaged and the chain slipped less under high torque.
A chain tensioner is a lot simpler to set up and maintain. Any other way of tensioning the chain, like an EBB or magic gear, usually requires regular maintenance to ensure the chain remains engaged.