As someone who has worked with bags and reviewed them let me chime in. You are getting a lot of personal opinions and prejudices.
The first thing you want to do is look at budget. There are some decent bags in the $175 range.
Next you have to decide what type of bag you want to use: two or four wheel. Both have their pros and cons. And what people use is what they prefer over the other.
I have used all types of bags including both two and four wheels. I am currently using a spinner. It's true that over rough surfaces you sometimes have to drag it like two wheeled bags but on smoother pavement--both inside and out--it rolls fine on four wheels. And since I've seen many smooth Europepan sidewalks, as well as rough ones, I'm sticking with the spinner.
The key is to make sure you get good wheels. Look at the type that are on bags like Away or even the Rick Steves Spinner. They are connected directly through the wheel into the bag itself. Get only those types of wheels. They are also easier to roll. The cheaper one, the ones that look like little balls connected to a plate that is then screwed into the bag are much more prone to breakage and handling problems.
I found with two wheel bags, my shoulder would start to ache from pulling it. Others may not have this problem.
My suggestion is simple. Try one of these two things.
1) Ask all of your friends or co-workers and see if any have a spinner you could borrow for a day. Then fill it with 15-20 pounds of stuff. (A weighted down spinner will act differently than an empty one.). Then go for a walk and see how you like it.
2) If none of your friends have one, some luggage companies will let you try their luggage for 100 days and if you don't like it, return it at no cost to you. Get one and try it out. You can always return it.
It really is personal preference. Neither way is right or wrong. It's just what is right for you.
As for where to buy them, many of the stores listed above are good--Marshalls, TJMaxx, etc. Just bring a tape measure with you because some manufacturers only includ the dimensions of the bag on their tags and do not include the handle and wheels.