As a self confessed Ebike and MTB junky, my two penneth is a hardtail MTB is a much more flexible and comfortable contraption than a gravel bike. Either assisted or not the tyres have the greatest impact on rolling resistance irrespective of bike weight or suspension. A Hardtail MTB with lightweight road biased tyres will be pretty much as quick as a gravel bike but a LOT more flexible in terms of what you can do with it. You ate then able to put a set of more aggressive tyres on and use it as a proper MTB.
Geometry lets you ride terrain, suspension just lets you ride it faster. So go for something with modern, progressive geometry for both greater comfort and terrain capability. It will also provide a greayer margin for error when you decide to have a go at something outside of your comfort zone.
All e bike motors fail.no iffs no buts. Brose are arguable the worst, bosch the best with Yamaha and shimano somewhere i the middle. The shimano and yamaha are down on power compared to the bosch unit. The bosch system is also the easiest to DIY or independantly maintain once out of warranty.
E bikes are not designed to be restricted. They are awful contraptions to ride on the road with the speed limiter fitted as you are constantly hitting the limiter, power cuts out and you either habe to work twice as hard to maintain 20mph or you ghost peddle at just below the limiter to maintain assistance. The limiter is only there to satisfy road law and IMO a 22mph limit would have been much more sensible. As it is all my amd my mates bikes are chipped/de restricted. Its essential if you are racing but also allows you to keep up with normally aspirated mates on flat sections of road.
Whatever you get, do NOT use a hose pipe anywhere near the motor, ideally tey to clean it as little as possible and ideally keep it somewhere warm and dry. My gang who use theirs off road all year round in the slop typically get 6 to 12 months out of a motor before water damage has killes it. My father in law who only uses his on the road in dry conditions has done 4 years with no issues but his battery has just died.
Conventional drive trains have no place on an e bike. They should be geared hubs on commuters or gearbox systems on mtbs. Geared hubs are currently available, gearboxs are on the way. (To the annoyance of Shimano amd SRAM).
E Bikes, good and shit. Great fun, great levelers, excellent beer scooters. Shit reliability!