What do you need then? (asides from soft-ish buttons)
I assume you were asking me about what to look for in a mouse?
It's not necessarily how soft the buttons are to push, though that can be important too. It's how the shape of the mouse allows you to push them. I think Logitech makes some of the worst mice you could waste your money on. The cool "ergo" shape makes for nice place to rest your hand, but encourages you to position your hand in a way that makes your fingers biomechanically inefficent for pressing a button and that means more strain on your tendons and muscles.
Think about the way you type. Try two finger typing with both of your index fingers fully extended. I'll bet your fingers get sore pretty quickly. A lot of mice have their buttons placed in a way so that you have to press them with your fingers in a near extended state. I own one of their earlier Logitech Laser MX mice and besides its awkward shape, the buttons are far too stiff. Perhaps the overall design has improved, but they seem to be rather fond of making mice inspired by SUVs.
For your average user, those mice are fine. They're actually pretty good mice that have awkward ergonomics. If you don't do design work or you're not a FPS gamer, they're fine, but if you use your mouse as a high precision pointing device because your work or play depends upon it, you'll have two problems.
- You use your mouse way more than the average joe
- You probably don't hold your mouse the same way
You have far more control over a mouse if you use your fingertips to move it around instead of using your whole wrist. The big mice become difficult to use this way. Low profile gaming mice like the Razer series allow you to comfortably use your mouse whether you're lazily steering it with your wrist or going for fine movements with just a couple of fingers and the buttons remain comfortable to press both ways.
I came to realize how crappy the big ergo mice were a few years ago when I was just starting my business and had a lot of 16 hour days. By the end of the day, I actually could not click and hold the button on my Logitech MX laser. I simply did not have enough finger strength left to hold the mouse button down longer than a few seconds after a long day.