I'm planning next years garden, and want to know what the most culinary flexible pepper to plant would be.
I plan on using peppers for canning & chili.
A very flexible pepper that is also good for canning is the hungarian pepper. It allows for a good usage in fresh, uncooked dishes. Additionally it sautes well, goes great in salsas, bakes well, is great roasted, or just eaten on its own (ok, that may be a bit much for most people). For canning my mother-in-law does it in different varieties with sweeter peppers, hotter peppers, a dill blend, and a savory blend and it's also a terrific relish once brought out of the canning.
Growing peppers of the proper heat level I think will be the most important.
If you like a lot of spice and grow Jalapeno peppers, then everything is going to taste like Jalapeno because you have to use a lot to get your desired heat level.
If you have the appropriate heat level pepper, then a little goes a long way in a dish and you will feel it much more than you taste it.
Here is a page with a nice list of peppers with ratings from the Scoville Scale (also explained on the page) http://ushotstuff.com/Heat.Scale.htm
Unless you're really space limited, why not grow several varieties of peppers? I've never regretted having access to more options.