It would be a boring life if we all thought the same.
So far, after much research, I have only found one single malt that I actually disliked. Tullibardine 225 Sauternes finish. It reminded me of the smell of the old rubber piping on the Bunsen burners at school
I've been very disappointed with laphroig "select" ie without an age statement. I bought a bottle thinking it a bargain but it was borderline minging, albeit I did drink it eventually. Their 10 year old is as good as ever (if you like that sort of thing), and still rather reasonably priced.
One of the very worst whiskies I've ever tasted was a dram from a £100 plus bottle of Ardbeg. Ironic really as I really like their mainstream 10 year old and their more youthful 5 year old "wee beastie". Also arguably the very best whisky I've ever had was also an Ardbeg which was a one off via the Malt Whisky society.
Lagavoulin 16, sadly a lot dearer than it used to be is another favourite, and their more modestly 8 is also very good. Coal Isla is lovely too.