[subtra3t]

I think for most people who want to get started with SRS, Anki is just fine. A lot of people like to hate its UI but I personally find it perfectly fine (and even good before the recent update where they forced drop shadows on random UI elements). It being available on every major platform is also a major plus point for when one needs to review cards with no access to their workstation.

That being said, the $40 is probably what holds most people back from using SuperMemo. If I had $40 to spend on SRS without feeling guilty I'd 100% use SM over Anki.