As far as panels go I have been saving in my favorites everytime I see a new company that sells. So here is what I have: Alfaparts.net, Cruiserparts.net (both new and used), realsteelcruiserparts.net, rockymountaincruisers.com, EBI, Heritage sheetmetal, SOR and Cool Cruisers. I don't know about any of the quality, but you can search and get a good idea. Also under the FAQ section there is a sticky on this.
I bought everything from the cowl back in parts from IPOR. They were easy to deal with and handled a mis-shipment very professionally. I found the prices to be very good compared to some of the companies you mentioned. The quality of the metal is good, however, they do not set up for the back door notch or side marker lights. There are no keeper nuts or even the holes for the hard top. Having said all that, if its a trail rig, you probably don't need those items. EVERYBODY'S panels need fabrication work to fit properly, so be prepared.