So, for me, a mouse is first and foremost, comfort. It needs to be comfortable since they get used for extended periods. Personally, the biggest issue I have had is a mouse that isn't wide enough, can never seem to find a mouse that accounts for (in right-handed mice) is support for Ring/pinkie finger right at the knuckles and first joints, and usually leads to cramping over time.
I agree with what Panda stated in terms of the perfect weight and that, and of course, it comes down to preference, I also agree that the G502 is one of the best shapes in the market because it fills in spots on the hand and provides support creating an overall much better experience of using a mouse.
The 3 points that matter most are the positioning of the hump itself, whether it is forward/backward, or off-center a little bit. Then it is the angle of the buttons themselves, how they interact with the grip and pressures applied. Then it is the sides of the mouse, probably the most important in my experience since most mice I've used my problem is keeping a good grip on the side, granted I sweat and lose that grip myself a lot of the time, and constant repositioning of the hand adds to the factors, but get the sides right, and you can build the top right IMO. Something that really interested me is the G600 that had a groove to accommodate your ring finger, right on the line that is the right top/side of the mouse. and I am more than happy to give up some of the width for the RMB to accommodate for this, the only problem is that groove needs to be formed properly so that the ring finger is acting as an anchor point and adds to the stability rather than just a resting place for the ring finger, because then your pinkie will for sure experience fatigue rather quickly.
With the weight, anything from 60-120g I feel is the sweet spot. Since the whole point of light mice is less fatigue and less weight to move around. I feel feeling the difference in weight only kicks in around 5g, not 10g as panda said, but having said that, once you are used to a mouse and you are just playing, that mouse becomes weightless essentially, because you are not focused on it and it becomes subconscious action. So that is where I agree with Panda saying the difference comes in at 10g because then you become aware over long periods of the effect the weight has on you/ your performance, and physical sate.
As for the mice themselves, only looked at the XM1 today. I really like the barebones approach, that really interests me, the inward grooves on the sides concern me but I see how they can work. Give me dat functionality.
Roccat I am rather interested in because of the bulkiness of the shape, although it looks simple and without much definition, I feel the shape itself will actually be more of a contender/ consistent shape than most as it aims at filling the hand and providing a fuller design rather than aspects that compliment the overall shape and only add to that section of the mouse and individual pieces like such eventually make up the entire mouse. Something I feel the G Pro wireless does really well too.
Glorious - Roccat all great mice, just wish the modular aspect of a mouse was not confined to its own mouse, the entire industry can benefit from that, so selfish in my opinion. CM seems good but the extensiveness of the hump seems a bit exaggerated and makes concern for the finger positioning/comfort, especially in a palm grip, It seems like your palm will half be floating in the air looking for a resting spot, although I haven't look into the mouse extensively either.
MX 518 meh, Air 58, good mouse/shape, but I feel the phantom was better, although I haven't really properly looked into that mouse. Razer, we've been waiting for them to make something that is actually good, and not just semi-comfortable.
G502 will always make me wet. and the G Pro wireless even more so, some would term that drippin'.
As said before, I want something that will fill out my palm and support ring/pinkie, because almost all mice cramp said fingers. If a mouse does that around 70/80g's I would be a happy human being.
