15's or 16's
 

In the market for rims what are better 15's or 16's I know that the 15's are a lot cheaper but does one offer more than the other if so what??

Tires will be cheaper for the 15's. You will need to run lower backspace on them to clear the calipers. Tire mfg's are moving away from 15" sizes, so your selection will get worse and worse. You can't run any of the upgraded brake systems. Some steering components won't fit.

16's will face some of the same issues, but no need to worry about caliper clearance.

If you plan to ever replace the tie rod with something stronger, 15s are probably too small.