Thank you, appreciate it.For the cheapest way to go:
You can get a new set of stock 17" JK Moab take offs with new stock Goodyear Wrangler highway tires for around $300 on CL or Offerup. (These came stock on JK's for years. And so many guys upgraded their rims and tires when they first bought their new JK. That there is a glut of them on the market. Thus the low price.) Cheaper if you just want rims and plan to run an off road tire. So in this case 17's are alot cheaper than anything else you will find.
You can of course spend more on the new honeycomb looking JK wheels (I think they're Rubicon). But with the stock MTR's on them they run alot more on CL ($800-$1200). Finding just a set of the rims is a little harder. But alot cheaper. If you want to just use these rims and buy your own new tires. That might run you around $500 for the rims.
In 15's look at 4WP's steel wheels. They have one that is sub $50 IIRC. That's just as cheap as the above JK take offs. But without tires of course.
It really depends on what your doing with your Jeep. Either way I would consider Duratracs or K02 tires. If your off roading. Or just run the stock tires on the JK takeoffs if your just using it as a daily driver around town.
If your rock crawling look for an aluminum rim not steel. Steel gets dings and bends to easily on rocks.
I had 15's on my Jeep when I bought it. And then put a set of JK takeoffs on it (those are the ones pictured in my avatar photo). I didn't notice a huge difference in ride quality. But I didn't experiment with tire pressure either. I think as long as you run upper 20's psi and use Rancho 5000X shocks your ride quality will be generally about as good as it can get.
Now I'm not talking rock crawling or heavy off roading. If that's your thing. Alot of guys run 15's off road. And may have better reasons for doing so. But like Chris said - that may not be that big of a difference between 15's and 17's off road.