Of the three you listed, I'd go with the JJ. You can set it up for indirect cooking without much effort. Keep in mind that you'll lose a lot of usable grate when doing this, so you'll be a little limited on the size port butt, brisket, rib racks, etc. Nice and portable to. There are also mods, as mentioned above to turn a JJ into a real smoker.
For what it's worth, when I first got into smoking, I used a standard 18" kettle and it did fine, but I soon realized that I needed more room and upgraded to a Smokey Mountain. If you're looking to start out on the cheap, there a usually quite a few used kettles out there for well under $50.
Whichever way you go, don't hesitate to ask if you have questions and happy smoking!