I've got a G400 (very similar to mx518). Logitech is a pretty safe bet since they have good warranty policies, as long as its in warranty they will replace faulty stuff without hassle. I find the more expensive mice with over 9000dpi , weights, laser sensors aren't really worth it.
Its worth having a decent mouse mat though, I got qck heavy. Plus if you want to be super keen then you need a mouse bungee to stop the cord snagging on stuff