Have flown both VX, AA on multiple transcons over the last six months. In my opinion, AA A321t F is hands down the best transcon premium product. The flagship checkin and lounges at JFK and LAX are a huge benefit (although as it doesn't exist at SFO it won't sway travelers there). The F seat offers a lot of privacy and I've always had consistently stellar service. While I appreciate the small cabin in VX, I simply cannot get over the lack of pre boarding amenities and lay flats. My rankings are AA F > B6 (rows 2/4) > DL / AA J > B6 (others) > VX F.