I profess no knowledge re. Professor Longhair...

I'll second Onhwy61: Queen Mary is one of my all time favorite recordings.
FWIW Prof spawned a generation (or two) of blues piano players in N'awlins. You may want to check out James Boooker's "Lost Paramount Tapes" which is my favorite record from any of Prof's "disciples".

Theduke makes a point, if you are going to build a collection, why not start at the beginning?

HOWEVER, if you're coming from a rock'n'roll listener's context and just starting out with blues piano , the later recordings are much more accessible - in particular Queen Mary - and a better place to start. One of the joys of migrating from rock music to piano blues is recognizing rock's roots in a different genre. About 15 years ago, I found Prof very rewarding for this reason and now listen to piano blues as much as, if not more than, rock music.

BTW New Orleans Piano and Madi Gras in NO are, as theduke notes, great records (I've managed to miss 1949 but will seek it out now).

Others not yet mentioned would include House Party in NO and Ball The Wall.