Key items to focus on for what you are looking for:
-50mm to 60mm (1.9" to 2.35") wide tires with a good hybrid tread for road and light dirt/trail riding - the photo above by Dallant is an excellent example.
-26" to 29"/700C - preference is based on height of you the rider and the performance you seek. More stable sharp cornering - 26". Roll 'over' and less rolling resistance - 29" or 700C. This choice is really personal preference.
-Gearing - Even with a motor it's great to have a good range of gearing. Road riding you will want at least a 42T chain ring up front with an (ideally) 11T smallest gear in the back. If your road, or in particular trail riding includes some steep hill climbs, having the smaller chain rings on the front to gear down to and climb with your motor will help you out.
On the note of gearing, many mountain bikes (OEM ebike and conversion friendly) I have found have only a 36T largest chain ring which limits you to 20-25mph/35-40kmph spinning at 100-110 rpm.
-Carbon or quality front shock. The only thing worse than a cheap solid front fork is a cheap front suspension fork. If you go with a suspension front fork make sure it's a quality component. Many bikes offer a Carbon front fork that helps absorb the 'buzz' of rougher road riding and light trail. Combined with 50-60mm tires at a reasonable PSI you will do well.
I'm a becoming a big fan of the OEM bikes available and learning lots from this forum. To date I have personally worked with conversion systems - Bionx and now ebikes.ca - allowing me to pick the 'perfect bike' for me first and then add the ebike elements to it.
The above suggestions come from picking the perfect road and light trail bike I built last year. I knew from my mountain bike I already had that the 36T chain ring was too small for optimal road riding. I'm 6ft tall so a 29" or 700C tire would not be a problem for me to ride on trails. Since my mountain bike had 50mm tires that I 'pre-tested' on trails and road I knew that would be a great width to consider.
For reference I built out a Giant Toughroad SLR 2 (2018) and the reasons I chose it are:
-Carbon front fork
-D-Post (seat post) technology for shock absorption on trails
-700C x 50mm tires with dual purpose tread for dirt and trail.
-Triple Chain ring - 22T, 32T and 44T up front
-11-34T 9 speed in the rear.
The above gear combinations lets me climb the steepest trails I have found so far and also cruise along at 35-40kmph @ 70-75rpm cadence.
I purchased the bike brand new for under $1100 CDN. I already had the Bionx setup from a previous bike to transfer over to it. If I didn't I would simply purchase the components from a vendor like ebikes.ca and add to the bike like I did.
Again, I have great respect and learning from so many here about the OEM choices available. Because I started out with conversion bikes I can only share what I found that worked for me - and hopefully the suggestions I have given here help you pick your perfect bike.