What do you mean by "best for games"? Features? Performance?
I have had both the G9 and IMO 1.1a and if I had to choose one or the other it would be the IMO 1.1a. Why? Because for me, when it comes to mice, the most important thing is comfort, and for me the IMO 1.1a was much more comfortable. There was nothing wrong with the performance, it was accurate, and it didn't skip or anything. Limited by 400 dpi but that is what I am used to, I play much better at that sensitivity. Because I could hold the IMO 1.1a better than the G9 I could actually play better with it too. I wasn't particularly used to either mouse, I got them at around the same time. I used a G5 for a long time before them.
Aside from the shape, one thing I did not like about the G9 was how hard it was to press the scroll wheel. This made panning the camera in DoW2 by clicking and holding the middle mouse button and then dragging very difficult. I would either have to mash the whole mouse down, increasing friction with the pad, or hold the sides of the mouse very tightly, which was not fun at all. A work around was to set left scroll to middle click, this made things better but it was still not so great. The IMO 1.1a on the other hand has a nice, simple, solid wheel that clicks easily. No problems at all with panning the camera in DoW2. The trade-off is sidescrolling. If you don't mind the simplicity then I don't see how you could go wrong with trying the IMO 1.1a, I got it for $13 at Monoprice. At the moment I am using an IME 3.0, which seems the same as far as performance goes, only the shell is different. It supposedly has a better sensor but I have not noticed. I prefer the shape of the IME 3.0 so that's what I am using.
I should mention that the IMO 1.1a does feel cheaper than the G9 or logitech mice in general, but the IME 3.0 feels more solid aside from the mushy "back" button on the side.
The G9 is great except for what I described. I wasn't a fan of the braided cable because it would tend to snag on the edge of my mouse pad and desk, but if you have a giant mouse pad it shouldn't cause trouble.
Oh, and the IMO 1.1 and 1.1a are the same thing except the 1.1a is OEM and 1.1 is retail.
