I got to say my best post-card is proably the most famous one portraying the Olympic, end to end being compared to the largest buildings (Woolworth Building) of the time. I would hate to think how small the Olympic-class liners would look compared to the World Trade Centre, if it was still standing.
One of my favorite postcards is the one that was reproduced, from historical photos, of Olympic and Titanic at Harland & Wolff, Titanic off to the side of the Thompson Graving Dock, with Olympic being pulled by one of the tugs.
That picture was recreated in a Harley Crossley painting, which I bought in 1996. I don't know how many copies of that painting are still available.
Of the postcards that I have seen of OLYMPIC, probably my favorite is from the Andrew Nash collection. A real-photo postcard of her attired in dazzle paint, and a seemingly overflowing passenger complement (War Time). Have a look see at - http://www.julesverne.ca/olympic.html
As for a favorite in my collection. However, it had the borders trimmed. A real-photo postcard of OLYMPIC fitting out. Three of her stacks are finished and her hull is about half completed with painting. Some folks (inc. a woman) can be seen looking up at her immense hull. A wagon is on station with what look to be prop fittings!
I had it blown-up to a 9 x 12 for my personal satisfaction. A beauty!
And for TITANIC, I was fortunate to aquire a pre-sinking real photo card of her departing Southampton. With a jewelers loop/magnifying glass, you can see a sailor still positioned at her portside well deck carane.
Being a perverse sort of character, I must admit that the French postcard of Olympic masquerading as Titanic has always tickled my fancy. I even saved it as wallpaper for a while. "Le Titanic", indeed!
The collection is a mixture of Originals, reproductions and actual snapshot type photographs that I have come across over the last 4 years or so. This webpage actually needs updating as I have aquired quite a few more since this went online.
Hope these are of interest.