Any bike will get you back into shape if yiou ride it.
MY opinion, I'd go with the 3.5 or 4.5 cause they don't have suspension seatposts and forks. as heavier riders, it's a waste and more likely uncomfortle while the seatpost bottoms out on the bumps. Plus as you develope, you will apreciate the rigidity of the non suspension. I've taken my mtb on paved trail for funzies while the wife rides her roadie. At speed of 19+, the front end tends to float around on the suspension forks. That's my experience but I sure wouldn't want that on every ride.
The 3.0 looks to be similar to the 3.5 you mention, but honelsty, I'd go with the next level up (4.5). A grade higher and 8 speed might be much easier to find replacment parts as far as rear hubs/wheels etc.
Oh yeah, on less expensive bikes, I don't have much faith in rear wheel durability as a heavier rider. I fth e shop does a good job adjusting the wheel after a few hundred miles, the hybrid wheel could last a good while. If not, could break spokes fairly quickly.