The only way to pick a bike from scratch is to ride a bunch.
I'm 58 years old , degenerative arthritis , bad spine , I bought a giant roam 3 to get back into riding.
I thought it was a good fit , but then I procured and old Trek 700 Multitrack.
The slightly more upright position and soft steel frame felt better to me than the roam3.
After fiddling with bar height and seat position , the trek is much more comfortable for me.
Now I'm a pretty small (light) guy with long legs so a taller bike is easy to handle.
If you're 240 lbs , a bike like the trek with 36 spoke wheels would be more durable over time than a 32 spoke wheel.
The Trek also has a 170mm crankset as opposed to the Giants 175mm crankset.
This makes a difference in the amount of leg travel per revolution as I turn the pedals.
I found the 170mm was more comfortable after say 20 miles than the longer crank.
So we're back to ride a bunch of bikes , make sure the shop sets the seat height properly for you , and take a good long test ride.
As we get older , fit is very important , lower handlebars are harder to reach , neck won't bend up very well.
When you find a bike that doesn't hurt after 5 minutes , take a good long ride and see if you get cramped up or hands go numb , etc.
I have to ride with my bars a couple inches higher than the seat , you may need something similar for your physical shape and age.
It's worth getting it right , be patient and methodical , you will really enjoy the final choice when you're done.
Mick