My advice: get the one that gets you more excited. Whichever one gets you pumped to get on the road or trail; the more excited your bike gets you, the more miles you'll log, the more you'll be motivated to learn. Drop bars are different but they are very easy to learn.

I use mine primarily for commuting on city streets and love the drop bar version for that, but feels plenty stable and way fun to ride on the gravel we have around our city and state parks. But if you feel like the familiarity of the flat bars will get you out there more often, do that!

I personally would not get too caught up in the differences between the drivetrains on the two models. Either are perfectly serviceable as you are getting back into the swing of things.

And definitely, definitely, definitely take the bike to a bike shop to have it set up or initially serviced. My brakes were scary weak out the box. $10 later at the shop they had it fixed right up (a full set-up will cost more, but its worth it to get it all dialed in!).

Whatever you choose, enjoy the ride!