I like .38 special and think it's a good choice for a first centerfire revolver.
If you can't fire different 38s, then just try them on for size at the gun store.
If you're comfortable with the 686 then fit for a K frame should be fine to. They have the same size grip frame.
While the $100 model 10 is a thing of the past you can still get relatively good deals on them. Police trade in K frames are also a good deal.
The one thing to be aware of is that recoil in a K frame will be slightly harder than with the 686.