Evidently YMMV, though obviously expectations play a role too, as I just had my first (one night) stay at the Churchill - contrary to some of the negative reviews I was very impressed.
My (u/g to club floor) room was ready for a noon check-in, and handled very smoothly and efficiently at the front desk when I turned down the offer to C/I on the 8th floor. Club lounge staff were super - warm, helpful and efficient. Yes, at breakfast, the 'one sided' lounge did get busy and crowded later in the morning, but the staff did a decent job of keeping things moving.
I had an issue with the room heating (the system would only cool), and the Eng staff showed up quickly, was also friendly, and had it all fixed in no time.
I did receive a lovely welcome note, big bowl of fruit, box of chocolates and half-bottle of wine.
My only 'complaint' is that the fitness centre is small and cramped, but Hyde Park is right next door...
For OsakaWino - I'd spent the previous night at the Hilton Park Lane, and although the hotel was fine, the lounge was also crowded, and the service was disorganized and frazzled. I felt like I spent a LOT of time waiting in line, and I was MUCH happier at the Churchill, as was my husband.
Enjoy your trip, whatever you choose!