Your team should really leave it up to your driver. There's code available online for both of these, so it certainly isn't a problem from a programming point of view. If your robot pulls to one side (this is prevalent in tank-drive robots with two identical gearboxes, wherein one side has motors driving in reverse and thus runs slightly slower), you might want to go one-stick, because straight lines are much easier to hold. However, you will find that cornering is a dream on two sticks and you can fluidly move around obstacles without slowing down. Two-stick is also quite a bit harder to truly understand so practice is very necessary. While it's certainly less intuitive, you should make the call early on whether it's worth it to learn two-stick
properly, or if you should just do one-stick, which, as was mentioned before can technically do all or almost all a two-stick control can do. It really is your call, and neither is superior. Though two-stick is better.
I have driven both configurations, and while my recent predecessors opted for one-stick, I went to two this year. One of the main advantages of two-stick is its excellent conduciveness to turns (in tank drive). In a one-stick configuration, one must apply forward motion with the y-axis, while also concentrating on slowly and nonlinearly moving the joystick sideways along the x-axis. This results inevitably in jerky turns on occasion, especially very sharp ones (two years ago limbo bar to ramp comes to mind), no matter how good the driver is. Of course, there's a lot less
thinking involved when driving one-stick by nature, so open space driving means you can just will the robot to a spot on the field.
Enter two-stick: it's much harder to control a jumpy or fast robot, but when going left around a corner for example, if you tap the left stick slightly back of centre (to apply some reverse current locking the left wheels) and at the same time throw some forward power into the right wheels, a very smooth, fast turn can be made. And just like driving a car, as you hit the apex, you can apply more and more juice to come out of the turn. You'll find you're rounding corners
very fast.
I need not remind everyone that your control system should adapt to the game and function of the robot. The best advice I can give is let your driver tell the programmers what he or she wants, because if the driver's not happy, the robot won't drive well.