Well, it really depends on the rivalry of the cars they make. (This includes American brands Lexus and Infiniti which makes sense as their sister brands)
Aygo vs Pixo - Pixo is actually similarly priced in higher specs, but Aygo has better build quality and shares a platform with the C1 and 107. The Pixo? It shares one with the Suzuki Alto.

Winner - Aygo
iQ vs Micra - The Micra is ridiculously average, does what you need to, but very boringly...the iQ is smaller but more clever and quite obviously more modern. And yes, you CAN fit in it.
Winner - iQ
Yaris vs Note - The Note is just a bigger Micra without the back end which it better looking. And that's about it. The Yaris is also very much similar to the Micra in that it can do what you want it to but it's not the most fun car to ever exist. However, what it can do...it does better. Which means it also does better than the Note.
Winner - Yaris
Qashqai vs Auris - the Qashqai has so much space, and yet is still considered a hatchback. The Auris, on the other hand, is just dull.
Winner - Qashqai
GT-R vs (Lexus) LF-A - two very technical achievements, but the LF-A has a V10 vs the GT-R's V6. You should know which gets the better sound...
Winner - LF-A
X-Trail vs Rav4 - the X-Trail does have a not-as-large-as-it-should-be amount of space, but is a better offroader. The problem is that they can't compare to the Freelander (obvious leader of the class) The Rav4's styling scores it the marks, no matter how false it is, but aren't SUV's about offroading? No advice past that.
Winner - X-Trail
Pathfinder vs Land Cruiser - Pathfinder looks rather like a downmarket Discovery, but it isn't as able. The Land Cruiser is also a better offroader and has a 480 lb ft V8 which has great offroading ability with the torque.
Winner - Land Cruiser
Murano vs (Lexus) RX - The Murano is pretty clean on the inside but it really isn't very fast. The RX is better on the outside, but it isn't very fast...either. However the RX is only available as a hybrid which I have never and will never like.
Winner - Murano
(Infiniti) G37 vs (Lexus) IS - Two strong saloons, with Infiniti providing a far, far better convertible and Lexus providing the better hard top. However, there isn't a model to compete with the IS-F...
Winner - IS
Toyota - 6
Nissan - 3