R.A.T. 6+

Fellow massive hand here, I use a Rat6+ as you can adjust the length and weight to fit your hand!

No one will suggest Corsair because the QC is bad and it's a brand people have decided to be elitist against (partly because most of the mice are heavy), but Corsair M65 maybe. There's also the Mad Catz R.A.T. 6+, but no optical switches. If looking for flat sides and maybe not short length, there are also the Corsair Glaive and Ironwolf, but again no optical switches. And the ROG Gladius II, which is hotswap (easily replaceable switches for when they break), but you already dismissed that option earlier. If you are strong, maybe the weight will bother you less.

RAT 6+/8+. Adjust them however you like and the issue with fatigue will be gone even if you plan to game the whole night

An Ironclaw is probably your best bet, but the finish tends to wear excessively fast and some issues with scroll wheels have been reported. I'm in a similar boat. I have a g502 Lightspeed, and while I am fine with the thumb button placements, I find my pinky and ring finger feel too cramped. The only mice I've ever used that felt spacious enough were the R.A.T. series. The R.A.T. 3 was the first (and best) of the series I owned. Bought it well over 20 years ago. My brother uses it on his rig this very day. I eventually got a R.A.T. 9, but the sensor was awful, frequent disconnects, etc. A few years later they were bought up and the new series released (even numbers instead of odd). I got a R.A.T 6 and a R.A.T. 8. They were both awful and suffered from the side buttons failing after 3-6 months. Ergonomically, they were great, but their QC sucked ass and killed the company. There are also vertical mice, or perhaps an Elecom trackball mouse. Those are fucking huge. Elecom is sort of iffy. Really everything is.

If you like comfort and pinkie / thumb rests, RAT 6+ , 8+ something like that would be a big improvement for big handed people like u (adjustable and swappable parts = big improvement) , hit me up in DMs, maybe I can find u a coupon or something to welcome you to the Mad Catz FAM!

There are cheaper items: RAT 6+ or 8+

If you want something that's actually able to be adjusted to your hand, check out the MAD CATZ 8+ or 6+ if you want one slightly less $

beyond a doubt, RAT series from Mad Catz, only things that actually adjust to you . Everything else is fake ergonomics.

I use madcatz rat 6.0 :d

hey you can check for R.A.T Series of Mad Catz. R.A.T 6+, R.A.T. DWS and R.A.T. 8+ adv. if you cna go little up in your budget then the latest M.M.O. 7 also is great choice. These mouse are feature loaded, for long term daily use and good in both gaming and normal PC use. I have used R.A.T DWS before, so i can tell that it worth a try. you can DM me is you need more help.