Fascinating thread. Maybe I am too easily pleased, or should get out more, but I can't see what is wrong with the Omega. It is large, quiet, comfortable, fast, reliable, cheap to buy and cheap to run.
It's old, and even good ones need money spent on them. Vauxhall's replacement isn't up to much(just like Ford with the Scorpio), and for me the big Volvo is the only one that has the same attributes of being comfortable, large, effortless, discreet, affordable and lacks the marketing wank of the German marques.
I like the S80, one I've seen is in budget, under 100k miles. Sadly it's half the country away from me, I need to sit/drive something more local, as I've yet to sit in one.
S80 has some cool tech (least one one I've seen) such as Radar Cruise,
but it will be a further depreciation hit, buying for £5k in a year or two I bet it's worth £2k. The CLS will hold it's value better.
The CLS for me, looks far better, it's got great driving position, loved centre console position, the dash layout.
I really need to drive an S80, otherwise I'm going in circles, as some reviews suggest a choppy ride at times in S80
Another factor is I will have to pay for suspension work on either, I'd do rear shocks but front's & wishbones I'd pay for. I'd rather take that hit on car I actually really like and love like the CLS, rather than S80.