Either Buckfast or Italian would be my choice for a beginner, but the thing to do really is try and find a fairly local source of good bees. Visit them and check out their behaviour etc. rather than just going by the "label". As Finman points out, there are so many variations.
I have two colonies which were sold to me as Buckfast, both from the neighbouring county so fairly local. They are medium-sized, attractive in appearance and very tolerant of bad weather. They both propolise everything into a solid matrix of gooed-together frames if allowed, but are also very clean when it comes to housekeeping. Good at slinging out intruders, as well. Both are productive and very good-natured, and not too demanding on winter food. So far they haven't shown any signs of varroa problems or dysentery. So they are recognisably the same kind of bee. However, they are clearly not quite the same as each other: one colony has some Italian influence, I think, and one is more Carniolan (greyer looking, more prolific breeders). The thing is, they will vary hugely due to outbreeding as soon as drones and virgin queens go off to mate, so unless you've got the whole population on an isolated apiary where they can't find other strains of bee, then any new "buckfast" queen could also be half Carniolan, Italian or whatever. I suspect that in the case of my two queens that had probably already happened. Photos are here:
http://www.beekeepingforum.co.uk/showthread.php?t=7225&highlight=pictures+bees&page=10
I'm very fond of my current colonies. They have done well despite an awkward year weather-wise, and have been extremely good-natured except when I was at my most clumsy, and quite manageable even when I annoyed them. I would definitely recommend them over Carnies for a beginner, just because of the very strong swarming tendency in some Carniolan colonies, which is great in some ways (more bees and honey!) but tricky to deal with if you're not used to it (they tend to bugger off unless you're really up to speed with swarm control...).
Whilst I like to raise my own queens, in this case I might go back to their original suppliers and get a Buckfast queen to re-queen both colonies, as they have both been so good. If your nuc doesn't turn out how you'd like it to, you could always splash out on a Buckfast queen from a good supplier, re-queen the colony and see how you get on with the resulting workforce?