The Wild Thumper 6-Wheel platform is the best of both worlds: It takes almost no time to go from un-boxing to rolling chassis, but it's also ready to be expanded on and makes great base stock for a serious 'bot.
Each of the six motors are mounted on independent suspension and outfitted with 75:1 steel gearboxes (no more stripped gears!). The motors are wired together on a terminal strip inside the 2mm thick anodized metal frame and can be controlled on two channels (left and right). The entire chassis is perforated with 10mm pitched, 4mm diameter mounting holes and there is plenty of room interior to the chassis for batteries, drivers and other support hardware. The chassis comes with 6 of those gnarly Dagu 120mm off-road wheels.
Because there are six motors total, each channel of your motor driver will need to be able to supply a decent amount of current to get things moving. This is a differential drive platform, meaning that a turn in accomplished by simply driving one side faster or slower than the other, or turning the two sides in opposite directions. Because the "pivot point" of this turn is essentially made up of the opposing three tires a gradual turn will require less power than a sharp one and the more power you can source, the more maneuverable your platform will be.
Zumo 32U4 Robot (Assembled with 50:1 HP Motors)
The Zumo 32U4 is a highly integrated, user-programmable and customizable tracked robot. It measures less than 10 cm on each side and weighs approximate..