That's a surprisingly hard question to answer. Everything and everyone has changed since Edwardian times. People dressed far, far beyond today's standards. Most of us would look like really bizarre creatures to them, not fit to shovel coal. Socializing, reading, writing letters and primarily dining were the recreations of the upper classes. You didn't gobble 10 course dinners and leave. There were probably hours spent chatting over these long leisurely dinners. Decor was handcrafted, real masterpieces throughout, the best of everything.. Axminster carpet, polished brass, beautiful woods. BUT as others have said - even having your own bathroom was not the norm in First Class and the bathrooms were very, very utilitarian by today's standards - salt water in the tub, fresh in the shower head (I seem to remember). There was no AC and heating was manually controlled.
Now, third class would think they had died & gone to heaven in today's cruise ships where everyone has their own private suite, bathroom, air conditioning and much, much better choices in food and entertainments.
Today, even the poorest of us on a cruise would seem very very well off to third class passengers. Today, even the most wealthy of us on a cruise would seem pretty 'second class' and common at best. All of us would seem vulgar, dressed worse than a fireman, openly discussing things that most ladies and gentlemen shouldn't even know much less discuss. Children behave like wild animals and even they are vulgar & foul mouthed & rude. I think an Edwardian might believe the world they knew had collapsed into utter chaos.
Which was more 'luxurious'? When you think about it, we're practically trying to compare two alien races.