With upwards of 250 cartridges that have been chambered for the Contenders the skies the limit. Depends a lot on what kinds of shooting/hunting you do or hope to do which cartridges, what barrel lengths and whether you'll shoot them with open sights or scopes. Much of the fun is the endless possibilities if your bank account holds out. Contenderitis is a very common affliction for many folks after they buy their first Contender, and some get it real bad. I was a stricken lost soul that owned nearly 50 frames and around 225 barrels from my first one bought in 1968, and the last 3 decades a lot of them wildcats.
Noticed you don't have any 14, 20, 24, 25, 26, 27, 33, 37, 40 or 41 calibers in either pistol or rifle calibers, so they might be of interest as there is a lot of them to choose from. All the JDJ's are excellent choices, as are all the Super Bowers if you can still find any. Re the 222 you mentioned, it does pretty well in a 14" barrel and will out shoot its 223 counterpart. Re your 17HMR, your only out to about a quarter of the range it will shoot quite well with a good scope.
L.