I use primarily Rimowa across all sizes, and only recently bought a B&R carry-on.
When I first chose Rimowa, I chose it mainly for aesthetics (sue me!) - it was pretty, and the various colors meant that I could spot it easily on the conveyor and was less likely to be confused with someone else's bag.
What I did find out, and have come to love, is how light it is, and what a workhorse it is. I've checked my 30-inch across dozens of trips in 5 years, most of them requiring me to sit on the bag in order to close it (that's what shopping in Europe does to you) and the zip has never broken, given way or malfunctioned in any way.
Wheels have also not given me any problems - it's been over water, cobblestone pavements, pebbles, small rocks (with some difficulty, of course) etc and survived. The cabin size also fit into most aircraft - I've only had problems on smaller propellers where I've had to gate check.
The ONE problem I did have (and it's cropped up several times) was with the lock. After some time, the numbers tend to misalign and your preset code doesn't work. E.g. If my code was originally set to 111, after some time, it would become 112 and 111 would render my bag un-openable. Frustrated me to no end, but thankfully, I have a Rimowa store near me and they will open/rejig the lock for you within 15 minutes.
What I would love to see Rimowa do is a nice external pocket for laptops and other need-to-have-at-security-knick-knacks. I know they have a model which has it, but it's fugly and has a tendency to tip over if your laptop is of the heavier variety. This was one of the reasons I switched to B&R, but now I am ready to give up my B&R because the heavy B&R aggravated a back injury when I tried to lift it up.