Agree with u/PhoneFresh7595, both of those are more commuter/trekking bikes than mountain bikes, so just making sure that's what you're after? If you actually want to hit trails, neither is gonna cut it. That said, between the two I'd lean Bulls Lacuba - they've got a solid rep for reliability and the Bosch motor is basically bulletproof. Kettler makes decent stuff but their resale value tanks harder and parts can be annoying to source depending where you are.