When I first had a computer and got an ISP it was Screaming Net, now I believe it's Tiscali and from what I read in the press not improved much from those days. Like the present Tiscali people now, I couldn't dump them then, they continued to charge and could never get through to their help line.
Since then I've been with BT with rarely any problems and probably about two outages in about 12 years.
I've always upgraded, from dial-up to broadband and now wireless with homehub and phone. Since being on broadband they have given me the hub and phone and reduced my payments without me threatening to migrate. All I did was sign for 18 months instead of 12 which I was happy to do. I can't remember when Norton became part of the package but it's been for some time now although I don't like Norton so don't use it.
I do use the free B.T. online storage/backup for music/photos though.
The only tempter that would cause me to change is the Sky T.V. but as I hardly watch T.V. and Her Ladyship says she doesn't want it theres no point in changing. She is happy with the hub phone where she can phone her friends in the U.S. and Oz for 1.5p a minute. I'm happy because I don't get outages and I know I have no limits on download useage.
Each to their own though and everyone has different experiences.