I have just written on another forum, the variety called 'Jelly,', they are the best and tastiest I have ever had. We first had them from a well known super market and last year I looked them up only to learn that they weren't being produced for the open market... but today we have bought two bags of seed 'Jelly' potatoes from a large garden centre.. Yeh!!
It's partly a matter of personal taste - some people like floury potatoes, while some (like me) prefer them a bit waxy. Here is a good database for choosing potato varieties: http://www.varieties.potato.org.uk/menu.php
Each year I have been searching for good tasting potatoes. So rather than growing one variety of first and second early and being dissappointed, I decided to grow three varieties of each.
This is because my local nursery sells most varieties loose at £1.40 per Kg. I have selected 12 tubers of Arran Pilot, Casablanca and Red Duke of York each for my trial with first earlies. I will do the same second earlies. I don't bother with main crop, as they are cheap locally. The cost was less than for a 2.5 Kg bag.
I have seen packaged varieties of 10 tubers for £2-3 elsewhere, so its a no brainer.