The list is long but a Cochran air integrated computer has to be the topper, along with an OMS canister light, I’m still mad about that.
I always find it interesting how people perceive what is good and what is bad.
I have used an Air II for probably fifteen years and I love it. Some people claim that they are awkward to share air with, like its something they have to do every other dive. In reality you can dive for a life time and never have to use it for sharing air. And if you did have to use it, it would be mildly inconvenient for a few minutes unless you’re diving beyond the no deco limits. Then you should not be relying solely on an Air II. I find the Air II a lot more convenient than having seven feet of hose wrapped around my neck. If however if I was in a cave and my buddy had to follow me out while sharing air, the original intent for the seven foot hose, I would defiantly not rely on an Air II.
When it comes to computers I like consoles. I have lost two wrist computes, one because of a strap failure, thank you very much Cochran, and one because I just lost it. I never forget my console, I never loose it, and I never get in the water without it because it’s attached to my reg. I ware it under my arm and under my BC strap so when I’m not using it, it’s not dragging or in the way. Plus my compass, SPG and computer are all in one spot, all very simple and very easy to use.