If your overriding interest is in World Traveller Plus Style or indeed any specific feature, then you are limited to those that offer it, whatever the price.
However, for those who may be interested in the price...The following is from a month long search at ITA for a 6-8 day ORD-LHR trip starting Feb 15. On 1/2 of the days the lowest fare is $530. On no day is it greater than $613. The airlines offering fares in this range are: AA, AC, AF, BA,
BMI, CO, DL, IB, KL, LH, SAS, UA, US, VS, etc.
I disagree with the idea that we should be so grateful for the offer that we shouldn't even discuss it. This is not an offer to fly free on a private jet. For Pete sake it is a commercial deal in which they do, and should, expect to make a profit. I do appreciate such offers, more options are always welcome, but I also see nothing wrong in analyzing them or comparing them with other options.