Best airline travel card – was delta now not so sure

I am wondering if my delta skymiles reserve card should be replaced-or at least supplemented by another travel card. For background I live in the Midwest and am typically flying in and out of a smaller regional airport to the major hubs-multiple flights per day to each hub-for all the major airlines. Currently averaging 5-7 trips a year and looking to maximize rewards/benefits of fairly heavy CC spend, $250k+/year.

I have been a delta reserve card holder for 6-7 years, alternating between platinum and diamond status. The first few years came with regular bumps up to first class and versatile points usage. At that time delta seemed like the top all around carrier from a plane quality and service perspective.

Over the past few years I feel like I’m drawing more negatives with delta than positives…mainly, flights seem to be expensive. Double the price of United or American. AND reward travel seems to be significantly more costly-demanding outrageous amounts of points for any tickets purchased via points. Regional jets seem to be outdated. Lounges are packed.

Lately I’ve flown a few legs with United and American. Both have had much nicer planes and their prices were less than delta by almost half.

So, I’m wondering what the best card(s) is/are to maximize benefits for someone who travels every other month and almost always has a layover of some sort. Lounge access is a big plus. Decent award travel, and upgrade options while earning miles and opportunities to improve status are good too. Wondering if I should stay with an airline specific card or go with something that can be used to transfer points to any carrier?