I used to live near EWR and travel a great deal to Japan for my job and I maintained NH elite status for a while. I book my leisure trips mostly with Delta because I have the Amex Plat card which gives me the access to SkyClub and that is enough for me to keep low tier Delta status. So I would say the Amex Plat card is a major reason why I kept Delta status while at EWR. The service from Delta is also better than United IMHO.

Now I relocate to SLC for a new job. The SkyClub is the only airport lounge at SLC, not to mention the long walk to concourse B to use other airlines. So I guess I am gonna stick with Delta for a long while…