What size guitar do you have now, or if you’re not sure, what make and model is it? What size guitar is “right” is, of course, a matter of preference, and in some cases it can be a balance of conflicting priorities. Myself, I prefer dreadnoughts for the sound, but they’re big, and my concert and parlor guitars are much more comfortable to play, especially if I’m sitting down. If I play standing up, the differences in size don’t seem to matter so much. I’ve never played a jumbo, and I have a hard time imagining it would work for me, but I’d love to be wrong. 😉
Ultimately it’s good to just get your arms around as many as you can and see what feels good. If there’s a Guitar Center nearby, they’ll be happy to let you try some on, and if you have any TAC folks in your neighborhood there might be an opportunity there as well. Best of luck in your quest!