My top five American TV shows were/are
Each one bloody outstanding - outstanding. I feel privileged to have seen any one of them, let alone all. Furthermore there were others, such as the Sopranos and Battlestar Galaactica, which were surely very good but I just never got around to watching.
My top five British TV shows were, it's more difficult, but I think:
Life on Mars
I've left something obvious off there haven't I? I've got a nagging feeling. These are different from the high investment US shows: less grounded, more absurd. They rely more on winging it. That's not a very clear way of expressing what I mean.
I think that TV has been art before now, but it's more consistent, and there's more money invested in it, now that the philistines have figured out they can generate income from quality. Of course there is another business model, which is churn out any tatty old crap which is supposedly 'real', while being nothing like reality. However, you don't have to watch it do you? (By 'you' here I am addressing myself)
I would like to put in a word for British short drama series, which come and go, perhaps never make as much individual impression as these great shows, but cumulatively add up to something worthwhile. That includes BBC classical adaptations like Crime and Punishment, and ITV's bleak crime dramas like Wire in the Blood and Rebus.