Crappy service
1. Crappy service/bad attitude on the ground and in the air (this sours my experience on United more than any other single thing). If that means switching out the current management team, so be it.
2. Progressive devaluation of MP, even while they literally give away EQM and miles through dozens of channels. I cannot use the SWUs I get unless I pay for business class. I wouldn't pay for business on United when there are better airlines. Starnet blocking is another form of devaluing my miles.
3. Lack of AVOD in all classes. This would be one way of looking past the frankly outrageous treatment that passengers in Coach get, and of overlooking the often shoddy treatment that passengers in premium cabins get.
Sorry for posting 3, but I feel they're related.