Ever since my G700 died last year I've been struggling to find a good replacement. I wanted 4+ thumb buttons, a good scroll wheel and something that would last. The last non Logitech mouse I had used was the old Microsoft intellimouse, which I would put right below the original MX518, which was the best mouse I ever owned.
Nothing from Logitech really interested me so I started looking at other brands. I ended up settling on a Corsair Dark Core RGB, as I found it on sale pretty cheap as a combo with the wireless charging pad. I figured I could live with only having 3 thumb buttons. Big mistake. If I actually used it wirelessly and had to charge it (wired), it would eventually heat up and stop working. If I left it on the wireless charging pad, I would have to wait a good 5 minutes and turn it off and on repeatedly to get it to start working.
Tried a Razer Naga Trinity next, which is my current mouse. Not bad, feels a bit cheap but it is light, and the ability to change out thumb button panels depending on what I'm doing is nice. I had heard nothing good about the software, but I haven't had any issues with it. I didn't even have to log in with a Razer account in order to use it.
Unfortunately it has now developed double click disease in the left mouse button after about 8 months of use. Combine that with it's garbage scroll wheel and I'm not going to bother trying to fix it, so I took a look at what Logitech has to offer now.
I think I've found what might be perfect for me, the G604. 6 thumb buttons and a scroll wheel that will switch between ratcheting and free spinning. The only downside I see is that it only works wirelessly and it uses a singe AA battery, which has its pros and cons.
The only thing I'd point out with that mouse is if you use a claw/fingertip grip it will be uncomfortable to the plastic protruding below the thumb. Palm group and those mice feel pretty good.
Logitech remade the MX518, and I'm really thinking about just buying that and using a bungie. Still to this day, I think it's my favorite mouse. I'm gonna give this Logitech G Pro Wireless another week, but I'm afraid my hands are a bit too big.