I've been searching luggage for a bit of time myself. Things have significantly changed since I did my last major international trip twelve years ago. There's a lot to think about.
First, weight and size matters. 50 lbs for checked bags goes fast. If you have heavy luggage, that's less that you can pack. We also have two of the largest sized bags which are 1-2" too large and would incur size penalties (and weight penalties if I filled them as usual). I've actually seen luggage scales for $20 or more so that people won't overpack.
When measuring, include the handle and wheels. I didn't, and now I've bought straps to scrunch the luggage smaller. The manufacturers may not include the wheels in their sizings, so be careful.
Some people are pro wheels and others are against them. They take up space, but getting around is so much easier. I got the 360 spinners on Atlantic luggage and I love them. We've gone on one flight with them and they survived. We'll see if the wheels on the checked bag survives this international trip.
We just ordered a bag from MEI that has straps to carry like a backpack but looks like a conventional piece of luggage. Proponents of this type say that wheels add weight and take away space. It comes in a carry-on size, for these folks also recommend that no one should check any luggage. We'll see how my husband enjoys having it on his back. Notice that I am not volunteering.
Also check the zippers. One style is superior to the other, though I cannot remember their names.
Try the Rick Steve's website and MEI. Happy trails.