I've had the InCase Protective Cover, ISkin Revo, Agent18 EcoShield, Seidio Rubberized Case, Seidio Innocase for Iphone, InCase Slider Case. Here are my conclusions:
1) InCase Protective Cover:
a) bad fit--loosens up over time, and doesn't completely seal around chrome allowing for stuff to get underneath and potentially scratch chrome.
b) great grip because its rubber type material
c) rather thick material
2) ISkin Revo:
a) great colors
b) pretty good fit
c) great grip
d) little too thick for my taste and I don't have any use for the clear protective cover.
3) Agent 18 EcoShield:
a) great fit because it is tight and not flexible
b) one of the thinnest, slightly larger than the InCase slider case.
c) pretty slippery, not alot to grip onto
d) nice matte finish
4) Seidio Rubberized Case:
a) very good grip
b) quite thin, and covers the mouthpiece and earpiece at ends which reduces face-prints from usage, and allows more grip when watching videos or surfing.
c) pretty good fit, but does show slight chrome. I really loved this case and had it on for months without taking it off. To my horror when I did, all the chrome was scratched to hell. I tried to buff them out, but they do not seem to be dirt, but real scratches. Very disappointing because I loved the case otherwise.
5) Seidio Innocase:
a) very good grip. I love the material used. Makes very easy to grip, but not too much that it sticks in your pocket.
b) Really cool colors--blue/black is a great look.
c) I would have considered keeping this one, but it shows chrome all around the phone. Problem is that the previous Seidio case scratched my chrome all to hell, so it looked like crap, so I couldn't use it. I needed a case that covered up the chrome.
6) InCase slider case:
a) the reflective black really highlights the phone.
b) fit is very good because it is a hard plastic that completely covers all chrome. Yet, tapered enough so there is no thick ridge around the edge of the phone.
c) grip is not so great. Pretty slippery, but with a little moisture in your hand it actually becomes pretty acceptable and much better than the phone by itself. In a cold dry climate it is pretty slippery, but still better than a nake iphone, mainly because it has edges that you can hold on to.
d) Definitely thinner than the Agent18. Hardly adds any bulk at all.
So, in conclusion, after many trials, I think for now I will continue to use the InCase Slider Case. It covers the nasty chrome scratches, has a tight fit, very thin, edges don't interfere with usage, so-so grip, does a good job with accentuating the phone, should be quite durable.
Hope this helps in your decision-making.
Zandian