The one I bought is in my signature. It is arguably the best one... after all I bought it
I suggest you find one nearby and buy it immediately. Does not matter what RK it is, just so long as it is a Road King. Preferences include hard saddle bags, cruise control, abs, upgraded seat, heritage style handlebars, and various other add-ons and upgrades too numerous to list. Of course, you will find that these "options" may or may not fit your needs in which case you'll forever be in the endless loop of buying stuff you think you need to make the bike better/fill the need of fitting in/becoming a poser/rub/etc.
Seriously, go out and look over what's close by. Mine was only 5 miles from my home. I mean you gotta get started on the important stuff of making it yours
jl