Whatever system you use setup is always going to be a pain in the ass.

Traktor scratch is good because you get to use traktor - which is great software.

Serato is great because its made by Rane and rock solid, software is proprietary though so no Traktor compatibility.

I got final scratch. Wrong horse to back... Traktor's great though, and final scratch just about limps alongside it.

I'd probably go traktor scratch meself. Better software, newer tech - you need a beefy laptop to run it though so thats another consideration.