I've been using the Roccat Nyth for a while now after years of using the Razer Naga. (Ya, I'm a MMORPGer, I need all the buttons I can get for them macros)
I though Razer's build quality was good, but Roccat beat them with this. The size can also be varied (it comes with 3 bits you can add to reduce or increase width) there are 12 buttons on the side but you can swap them out for 1 large, 2 large or several medium to small buttons as needed. And, best of all they support 3D printed parts so you can technically mould the mouse to your needs.
The sensor and buttons are plenty sensitive and easily adjustable on the mouse or in software.
Speaking of which: Your profiles are stored on the mouse itself - so unlike Razer who store profiles in the cloud, you don't need to worry about losing net, their servers going down for days (as happened last year), or about software compatibility with other OSes (yay for us Linux users )