Can anyone recommend a good, light weight transport wheelchair to use for doctor appointments, taking mom out etc.?

I bought the one that Walgreen's carried and it gave us many years of use. Still have it in storage for someone else who might need it. Eventually she had to "graduate" to a regular wheelchair. We started off with one from Walgreen's, then bought one from a DME provider, then hospice rented one for her that had features she needed. I will say that the small wheels of the transport chair are excellent for what you mentioned, but don't handle rough terrain.

I bought mom a Hugo years ago which she now mostly sits in all day with a cushion seat - it folds up easily and she can scoot around in it as the wheels pivot

I second the comment about the small wheels, they are really not able to handle more than a few feet down a rough sidewalk nor are they easy to manoeuvre over door thresholds. I used an inexpensive foldable wheelchair and was able to lift it into the trunk fairly easily.

Ours is Medline Excel...it is the red one with the little larger back wheels. It is much easier to get up and down curbs than the regular transport chair. We purchased it from Amazon for about a hundred dollars 2 years ago. Mom has gone everywhere in it ;-)...track meets, shopping, church, the park, you name it.