What many of us eventually end up with is two sets of wheels/tires. The 20s for the street and mild off road logging trails or the beach (there are several alternative very good tires now), and 18s for more serious off road and or winter.
For 2011 it was way less expensive to purchase a WK2 that included a OEM 20 inch wheel package and then buy 18 inch wheel/tires and skid plates. If you also want front tow hooks, the difference was not as much. There may be an ELSD availability issue now, however, that forces you into an ORA package unless you are looking at the summit. V6s wouldn't have that issue as ELSD is not available even if they had enough power to spin the wheels
As far as 18s vs 20s, been lots of discussion threads. Soft/hard comparisons are BS, my 18s ride harder than my 20s, but turn in is still sloppy. I can't wait to take off the 18s and put on the 20s as the 20s feel and perform so much better on the street and make the WK2 look so much better.
If you can't afford to do both wheel sizes, pick the one optimum for your kind of use. There are many here that run 20s on and off road and are well pleased.