I think it depends on what is available in your area. Do you have local shelters or hospitals that take donations? Is there a place to drop off quilts for organizations like Project Linus?
It also depends on whether you like to "do your own thing" or follow someone else's requirements. One of the reasons I like Project Linus is that they always seem to appreciate a wide variety of quilts, and I like to be able to make whatever pattern or fabric that happens to catch my fancy.
If you do make quilts that would be loved by preteens or teens, I'm sure those are probably in short supply almost everywhere. When people make charity quilts, they usually think of babies or small children, and their quilts reflect that. Quilts for older kids would be especially great.
Blessings to you for thinking of others!