If you are just going to ride trails then probably the fuel ex5 would be fine, I do have a trek roscoe 8 (2019) and it's really playful and fun, i recently changed out the suspension though, if you want to do harder trails (rockier, jumps and drops) I switched to a 27.5 150mm revelation, it's a huge upgrade, the 2020 already has the suspension sorted, looks like a budget revelation.
If you don't want complications with the boost 141 hub go with the fuel ex as it has a rear boost thru axle. the brakes on the ex5 are more budget friendly, the mt200's (roscoe 8 2019 brakes) are a good brake for a light rider, whereas the 2020 roscoe has the mt500's a more powerful but not a huge difference they also have a bit more modulation. Deore SLX is probably the best bang for buck.
The Deore drivetrain would do the job, if you wanted something with a better clutch or shifters, you can always change to a sram NX eagle as that uses a shimano freehub body.
The ex5 has a boost thru axle which would is a lot stiffer and easier to change the hub/wheelset. the geometry seems quite versatile for really anything on both bikes. the 2019 ex5 has a 51mm offset which is probably better for 29er's. while the roscoe has a 42mm offset, which would make the bike a lot more stable, but then fuel ex would have the dual suspension.
For the price I'd go with the fuel ex so you have more flexibility with the rear thru axle, i think it's a great deal.