I am using ReSharper since version 3 and I always used InteliJ Idea/Resharper 2.x keymap schema. Recently I have learned Ilya's Visual Studio keymap. They each have advantages.
What keymap do you use/prefer with ReSharper?
I think it's mostly going to depend on what background you're from. Personally I found going from Visual Studio to Visual Studio + Resharper very easy using the Visual Studio key map (not suprisingly). Someone coming from an IntelliJ background is going to find the IntelliJ mapping easier.
If you're new to both Visual Studio and IntelliJ I would suggest going with the Visual Studio mappings in case you find yourself in the horrible, horrible situation of having to use VS without R#er in the future.
Most people will supplement the default bindings with a few of their too - so if you're really missing something from one the just add it to the other.
Typically I use the IntelliJ mapping, simply because that's what was introduced to me when I started at my company, plus a few additions:
The simple answer is 'it depends'; most developers I know (and I include myself in this) are creatures of habit. When developing, I tend to find that my 'muscle-memory' takes over when I'm performing tasks, whether that be using ReSharper keyboard mappings or the choice of CLI to use when doing simple command line tasks.
Both keymaps have their own advantages as you've stated, but the biggest advantage is how productive it makes you without getting in your way. Personally I use the Visual Studio keymap, because that's the one I know and for 90% of the tasks I need to perform with ReSharper I don't need to think about the steps involved in activating them (Ctrl+R Ctrl+V to introduce a variable for example).
If you have a Visual Studio background go for that one. If you have a Java background go for IntelliJ.
The Visual Studio one does have the advantage that other developers who want to use your pc for five minutes don't have to pull their hair out. but even then some hotkeys are different.