The toggle-able free-spinning scroll wheel on the M705 was a game-changer for me. When I got the mouse, I was working for a place that had a lot of buggy spaghetti-code programs that interfaced with a massive database, and I often ended up manually scrolling through million-row tables in Toad correcting broken or missing data. It made my life sooo much easier.

I later upgraded to a MX Master ($100) which automatically enables free-spinning mode when you scroll quickly. It's fully adjustable, and it works super well.

I use this one as well. I think it's my long term choice. I got one for work and home. Battery lasts ages, wireless is pretty good. I do notice that a big ol' wifi router next to it will interfere...