Ah, the other thread was deciding type of bike...this one on these two. I do think a hard tail MTB is a great option for you.
I thought you mentioned one of the dealers was going to add a second wheel set for you. What I would do if I was going to ride my MTB on pavement for anything more than a couple of miles.
Did you see Court's review on the Cube? Might help you decide.
You have a local dealer for each? Did you get a feel for preference dealing with either? For me, that's what I would buy on, cuz the bikes are more similar than different. Both are excellent bikes.
And yes, either will do your trails nicely. And with some road tires either will do pavement pretty well too.
To give you an idea, range on my Explore is about 50 miles on level 3. The trance with the PW-X motor, offroad, all level 3 with some 4 and hills, is about 30 miles. Either can be extended by riding in a lower assist level, and keeping the speed down. Most of us tend to ride them at the speed limit unless terrain won't accommodate it. So unless you're trying to stretch it's range, you just ride it to suit, plug it in when you get back.
One feature on the Trance I like is the 6ah charger with a button to stop at 61%, which is a 'storage charge' - where you want it when you put it away. The Explore has a 4ah charger, you have to turn it off if you don't want to charge all the way. It's best to store the batteries at 50-70% charge state.
I've heard of Cube but no personal knowledge, so I can't compare the two brands. But what I do know about Giant is they are the largest bike builder in the world, and you get a lot of design expertise and a quality build, great components, with a great company to back you up. If the dealer is any good it's a safe bet. I see Cube is from Germany - so you'll likely pay a premium for that. I don't care for the small front chain rings - they have pretty much done away with those for all motors for 2020.
The Fathom has the 'sport' motor which is the yamaha PW SE designation - slightly less power, slightly less cadence assist than the PW-X, but it does have the bigger 500w battery pack. It's the same motor I have in my Explore and I think it's terrific.
Trek also uses the Bosch CX and they are on Gen4 for 2020. Their Powerfly model for 2020 is now a hardtail. It may even be possible to find a leftover '19 at a discount, they had a couple at my dealer. I got my Trance at about 25% off list, zero interest for a year. It's a pretty painless way to buy an expensive ebike.
Neither one of these bikes have true MTB forks, but either are pretty good for what you want to do with them.
As an aside, San Diego Fly-Rides dealer has the '19 Cube Reaction Pro 500 on sale for $2295 USD:
https://shopsandiegoflyrides.com/co...es/products/2019-cube-reaction-hybrid-pro-500