UA is bad in many customer related areas but not abysmall. Their competition generally is about the same. Those competitors that do not share the same flaws generally possess other great weaknesses because of their lack of size, lack of network, lack of partners, lack of excess aircraft when things go wrong, lack of interline agreements for when things go wrong, and most importantly on FlyerTalk
, lack of a competitive frequent flyer program.
As for lost luggage, UA has about six bags mishandled for every thousand passengers. Its unfortunate that your friends were part of the 6 rather than the 994.
The area where UA consistently lacks especially for the non-elite is phone support. Everything from reservations to lost luggage to mileage plus over the phone is a disaster. But some of UA's competition are no better.
The primary reasons for a non-status passenger to fly UA are:
#1 their route network.
#2 E+, J, and F classes, especially long-haul.
#3 the MP program, especially if they are willing to combine miles from partners.
(It is possible for an infrequent flyer to
always fly free using UA miles and get everywhere they ever need to go. Sometimes Saver; somtimes Standard awards.)
The top four carriers according to the AQR article, Hawaiian, Jet Blue, Air Tran, and Frontier cannot compete with their comparitively minute route networks, no comparable premium seating, and inferior loyalty programs.
Summary: Better in some ways, worse in others.
The correct question is not "who is best" but rather who is best for X, Y, and Z needs.