FlyerTalk Evangelist
Join Date: May 2012
Location: MCO
Programs: AA, B6, DL, EK, EY, QR, SQ, UA, Amex Plat, Marriott Tit, HHonors Gold
Posts: 12,809
To my knowledge no hotel or car rental is really going to help you that much towards getting medallion status. The only things you might get will be a small handful of RDMs on car rentals or hotels.
My preferred hotel is Marriott (despite a number of recent shortcomings) and my preferred car rental company is National (I like the executive aisle selection option).