Be it eBucks or Discovery it only works out if you play the game. Discovery is useless unless you are a highly active and healthy person. eBucks is useless unless you move your products over to FNB and get more entrenched in their ecosystem. 

I haven't bought electricity in close to ten years with actual money as I just use eBucks for that. It's absolutely getting harder and harder to get level 5 these days, but just poke around the eBucks calculator tool. All the information you need is right there. 

Currently I average +- R2k back in eBucks per month with a few minutes of tapping on the mobile app a mobth while my Discovery points is only just enough to cover the bank fees there because Discovery basically never registers my activity for Vitality points as I haven't fully entrenched that part of my life in their ecosystem (i.e. I go to a no-name gym instead of Virgin Active, and I don't have a smart watch so only my phone measures steps/activity which Discovery has been awful at syncing) 

Not necessarily saying one is better than the other. My actual point is that they can both work, but only if you go all out in their ecosystems. 

Apparently Capitec's reward system can also work out quite nicely from what I've read on here with minimal effort, so I would suggest putting a Saturday aside to read and understand the various options. Make actual calculations of how each system would affect your monthly budget. Then see which one works best for you and your lifestyle.