What are you having it with?
I've got a rather excellent
Alvear Pedro Ximenez 1927 Dulce Viejo, which goes beautifully with desserts and cheeses (try it with
queso Cabrales).
I've also got a rather nice
Williams and Humbert 12 Year Old Oloroso. Very good as an apperitif or with nibbles, such as nuts, olives or anchovies. Also very good to cook with.
I can also recommend the
Lustau East India Solera. A blend of dry Olorosso and sweet Pedro Ximenez. Great with chocolate desserts and blue cheeses.
If you really want to push the boat out then I can recommend the
Alvear Amontillado Viejísimo Solera Fundación - but it is spendy! A cheaper version is the
Fernando de Castilla Antique Amontillado Sherry which is very nice as well. Good as an aperitif.
If you want an alternative to a sherry, I can also recommend the El Grifo
George Glas. I'll see if I can track down a UK stockist. It's a sweet red wine that is excellent with desserts and cheeses.