A few thoughts ...

NW's First Class cabin/services are not much different from WBC, in my view. I only flew twice or three times on F/C but they even had the same menu. The seat, however, reclines more than WBC and spacious.

This is a major difference from UA.

This is off the topic but I also think UA treats its top-tier members far better than NW. Waitlist priority is not that significantly different from Gold, etc.

I am not flying as much as I did last year after switcing to UA.