I've tried to switch from UA to DL because DL is probably a bit more convenient for me on the east side of Manhattan and the lounges are much better but they have made it hard. I had to give up on trying to book a TALT because I wanted to use two vouchers and while I kept getting preauthorization notifications from my credit card nothing booked. Phone had a long wait and the text chat was patronizingly useless. UA IT and iPhone app in particular are years ahead. The irony is I have status with UA and could probably talk to someone quickly but I never need to, whereas with Delta I don't have the status and it's both necessary and impossible to talk to someone.

I've come to the conclusion that if it is a really simple journey and I'm not not likely to need any support DL is viable. If I suspect it might be complex (e.g. connecting or potential voluntary change) it is just not worth the effort and I will stick to UA.

But the greatest liberation is still just booking what you want. I never thought I would fly BA again TALT but had a look the other day. Lots of time options, low cost, new club suite, booked and less desirable DL timing cancelled within 24 hour period.