I haven't grown any of the varieties so I can't really help but I heard Cristo is a very good variety for storing. I decided to plant Cristo this autumn but will buy bulbs from my local garden centre in the autumn. I saw packets of 3 huge bulbs for 2.99 per packet last year, much cheaper than T&M.
Do shop around before you decide to order, as T&M might not be the cheapest place to buy from.
For example Dobies has Solent Wight and Purple Wight. 2 bulbs for 3.45, postage free. :)