I like speed, so my A rig gets the most use.
This is mostly due to the fact that our pond is surrounded by trees so we seldom get good steady hard winds, so it is only occasionally that conditions are good enough for the B rig,but when that happens, it's a blast!!
The B rig is more versatile and can handle a greater range of conditions, but it's severely disadvantaged in lighter airs.
I would buy a good A rig, and invest a bit of time and effort in making a B rig; polyester film is cheap and available from PJSails, as is the double sided tape for joining the panels.
Even if your first effort is a bit heavier than it should be, when you need this rig the wind will be strong enough that it doesn't matter.