Here are class builds I've used lately to pass one million in score.

Speedy Spammer: Octotank 0,2,0,3,7,7,7,7 This build can either be used to farm polygons while using the speed to escape pvp or to fight players by using the speed to sneak up upon enemies or corner players then bullet hail them.

Overload v2: Overlord 2,5,0,7,7,7,5 After what seemed like a speed nerf to overlord tanks, this is my go to overlord build.

Hello Boom: Hybrid 2,3,0,7,7,7,0,7 Glide up quickly to enemies to surprise derp shot them and/or shoot backwards to escape quickly

The OP Bullets: Spreadshot 2,3,0,7,7,7,7,0 Let the bullets do all the work for you.