If a game is made with gamepad in mind, then absolutely gamepad is the first pick. Mine is an XboxOne wireless controller. I don't think I have any particular brand loyalty, but I like the layout.

Most games I play are mouse and keyboard though. I'm using a wired mouse with a 60% mechanical keyboard. The keyboard took a bit of adjustment, I used to use a full-size board and thought I'd be miss having some of the keys, but for gaming it doesn't come up too often.

The biggest game changer for me was a desk mat. Upgrading from a mousepad gives you far more real estate, and using a smaller keyboard helps there too.

The mouse is a Cougar Minos X3. I used to use a lot of Razer products, but honestly I've been disappointed with their build quality. This one's a lot like the Deathadder series, and half the price. I like a mouse that has M4/5 on the thumb, they're handy for binding a couple of keys to.