Of those three bikes I think it is a coin toss between the Jamis and Trek bikes. For the kind of riding you do a suspension fork will do little more than add weight so forget the Specialized. Additionally, if either Jamis or Trek makes otherwise comparably equipped bikes with rim brakes then you might look at those as well. Based on the kind of riding you plan disc brakes are probably overkill and swiching to rims could save some bucks. And your bike will stop just as well.

I ride a Giant FCR on gravel & dirt trail as well as paved rail bed trails. Switching from the stock 700x28 to 700x42 made a huge difference in off-road ridability so you should consider switching to 35 or 38 at the least. Check the inner rim width to determine the outer limit for tire size.

Welcome back to bike riding. After many years of riding just road bikes I finally switched to a hybrid and love the flexibility so much that I'm getting ready to sell that old carbon frame.