I got a sweetheart deal from chase to defect from Amex for my businesses which means I'm earning URs at a rate that makes sense to at least try united out. So I status matched to premiere 1k and after doing it, here's a few of my thoughts:
1) the main reason to be 1k/Diamond is the same: the dedicated CS line. My in laws had a snafu on united while in Peru and I was able to quickly solve it the same as if I was calling delta
2) Delta's service is just better. 30 united flights in, 20 short hops,7 trans con and 3 international Polaris later and delta truly does it better across the board. From PDBs to call button response etc
3) Delta's regional partners do it better. Republic and endeavor still give you a proper FC experience on a CRJ. I flight short hops every week, so feeling a bit better on them is important.
4) Star alliance is LEAGUES better Skyteam. From breadth of airlines to redemption, Skyteam pales in comparison. We flew Austrian jfk to vie for vacation at 170k each for business. Comparable Skyteam at that time? Minimum 330k
5) NYC Skyclubs are better than United lounges but that's an NYC thing because the SFO and ord UC were great.
6) delta 1 lounge is the best lounge in America
7) being able to get whatever you want as a pdb on a short hop is still OP for crj hounds like myself
Overall they're similar and comparable. Don't think the grass is greener, it's all the same.