As a Lexus and CX-5 (first time Mazda) owner, I actually don't think it is an unfair comparison. The CX-5, Tucson, and NX are the best looking CUVs on the market and it's not close in my opinion. (I think the German brands are satisfied putting their label on an otherwise bland looking car and saying, "There. Now you can buy a CUV from us, too." They are essentially brand-loyalist cars rather than category leaders.) So then the question becomes, how much better is the Lexus at any given thing, and how much do you value that? For me, it came down to exterior looks, interior looks, and driving.
- Exterior - already discussed. I like the NX a touch more, but there are a few things I strongly dislike about it to. I think the NX looks may not hold up as well if you plan to keep the car more than a few years. The CX-5 is more understated, but has classic lines and will look great for a while. The Grand Touring's larger rims help contribute to a higher calibre look.
- Interior - On the Mazda side, I noticed a big difference in quality "feel" going from the Touring to Grand Touring - the leather seats and particularly the different, higher-quality inserts around the cabin contribute a lot to making the car feel more premium. (You need also need to get the upgraded package to get the leather, wood, etc. for the Lexus.) The Mazda dash is much simpler than the NX, but I don't count that as a negative frankly. What you do start to miss are some of the entry-level lux features like power liftgate and memory seats (my personal pet peeve since it's available in Europe).
- Driving - CX-5 is fun to drive. Period. It's a little louder than a Lexus, but not bothersome to me at least.
For us, leather and navigation were requirements. So we were looking at a $12-15k price difference and didn't feel like that was anywhere worth the cost. Like many, I've also found the sound system to be really weak...but I haven't said anything to my wife, who thinks it sounds "great." Mazda is also new to many people, so I've had fun introducing people to the brand.