My first FF was Deathtrap Dungeon, hadn't seen anything like it before and my village library stocked loads. I took House of Hell on holiday when I was little - it rained for the entire week so I stayed in and read it and never managed to complete it. You had to get the Kriss knife to kill the bad guy, I knew it was under some stairs but was never given the option to turn around and look when I'd descended. Infuriating!
I also did some of the novel/advanced ones, the series of 4 - they were quite good I think. I remember getting to the very end and not having all of the crowns (you had to collect 9 or something).
Fabled Lands sounds interesting but I only discovered these very recently.