This all depends on your spending, redemption options, and valuation of benefits. I'm relatively informed in this space, and have access to the Platinum, CSR, and Ritz currently. I hope to have the US Bank Altitude Reserve in the coming weeks, but I haven't used it yet.
For pure benefits, I think the Platinum is the best. Full featured, but the AF is high. It is a relatively poor earner, but has a good bonus and excellent transfer partners.
CSR (and its partner JPM Reserve) is probably the most popular premium card. It has an extensive benefits suite, great earning potential, good transfer partners, and an easy to use travel credit.
Ritz Carlton can be perfect or awful depending on your desires. Earning rate is the lowest of all the cards I'm listing, but redemption options are reasonable. Great benefits suite (even more extensive than CSR, on par with Platinum,) but difficult redemption of travel credit. The opportunity to get top tier Marriott and SPG status at a reasonable spend level is high value to me.
US Bank Altitude Reserve has a good bonus, reasonable redemption, good benefits, the lowest effective annual fee, but no transfer partners. Earning is outstanding if you use mobile wallet tools with frequency.
Citi Prestige is fantastic if you stay in hotels for 4 night stretches. I don't (always use Air BnB for longer stays,) so I don't like this card. The insurance for trips, purchases, etc. is top notch and the other benefits are in line with the other cards in the premium space. Transfer partners aren't quite as good as Platinum or CSR, but this does pair nicely with other Citi cards.
There are a few other Visa Infinite cards that would also be top tier (UBS and City National each offer one off the top of my head,) and a handful of premium airline cards that only make sense if you're a very frequent and loyal flier (Delta AMEX Reserve, United Mileage Plus from Chase, and the Citi AAdvantage Executive.)
I don't personally think the Barclay's Luxury card lineup is competitive with the above mentioned cards. Fees are high, benefits are minimal, and earning is average. I'd be happy to be proven wrong and find another option in this space.
My wrap up: the Ritz Carlton is the best fit for me, followed by the AMEX Platinum, USB AR, then the CSR. Prestige and other cards listed aren't high enough value for me to consider outside of a signup bonus.
