ZKV > ZKIV & ZKVI
TO me, the Zoom Kobe 6 is the weakest out of all 3 in terms of overall performance. But it's a close tie between the 4 and 6 though in terms of fit and cushioning. The biggest problem that I have is the heel cup. To me, the way they sculpted the whole heel from the back and around the ankle is pointless. Sure it extends around, but for what? Last years Kobe 5 focused solely on the heel which was enough and because of that, it kept my heel locked in check.
But after 10-15 wearings on and off the court, the cushioning around the heel area does and will continue to mold around my ankle. I also have to use the runners loop (google it) so that my ankle is locked in more than a regular knot for basketball.
Traction is better than the 5 but not as good as the 4. I had a lot of doubt in the 6 because they got caught up in the whole black mamba snake print and applied it on the outsole. The Kobe 6 has more squeak and sticks to the floor a lot better than the heartbeat pattern on the 5. Whether it's indoor or outdoor (mainly indoor). I wouldn't recommend playing basketball in these for long hours outdoors if you are planning to. Soles are strictly indoor only.
Cushioning has improved. Same set up, different feeling (slightly). Heel Zoom is felt a lot better (maybe it's just me). If you remove the insoles and look inside, you can actually see the outline of the Zoom Air bags. Met bag in the forefoot and a regular zoom air cushion in the heel. Keeps the shoe light, yet responsive. As you take a step, the amount of force you put onto your feet is pushed right back onto it ready for your next step. Heel to toe is a lot better in the VI as well. Probably because of the higher base and lower front...
Breathability is great. Upper is made out of the scales, mesh, and flywire. Keeps the shoe nice and breathable especially the tongue. Uses the same tongue and inner-bootie as the ZKV. It hugs the top of your feet very snug allowing that one-to-one glove fit.
The fit on these is a little different. I feel that the upper hugs the foot more allowing the shoe to be more flexible, but not greater than the 5. I don't know how to really explain it but when you tie these up tight, the shape on the kobe 5 molds a little better. Maybe its personal preference but it's just a different feel. I like like the skinwire feel rather than the scale upper on the 6. The tow box room is much more wider allowing more movement for yours toes. The Kobe 5's have a more narrow space for your your heels resulting in a better fit and lockdown for heels.
If it came down to choosing the best overall shoe for me, i would go with last years Zoom Kobe V (5). Just because the VI is the newest shoe, doesn't mean it will surpass the older model. Each year, Nike will always strive for a better, lighter, agile, and faster shoe for Kobe Bryant which they are doing a superb job at. The Kobe VI may be more suitable for others than it is for me. Each to their own since this is strongly from my perspective and personal experience with the shoe. Hope this helps!