hmm... if I was torturing someone for the sake of revenge or anything other than to get information this is what I would do.
First I would chain them up in a pitch black room with a good echo. Have a leaking faucet going 24/7 into a bucket and have another faucet driping salt water on their head. Leave them alone for 2 days without food or drinkable water. Afterwards every 5 minutes I would stab the person with a fishing hook and leave it in them. After a few hours of that, I would start riping them out one by one. After all the hooks have been removed I would pour a bucket of lemon juice on them. After all that if their sprit isn't broken yet, I would proceed to cuting off 1cm their finger and burning the wound shut every 10 minutes until one of two things happen. They are reduced to an hollow shell of who they once were, or they die. Either outcome works for me.
It's not simple nor is it humane in any sense of the word but I'm pretty sure it would be effective. My mind is a fucked up place and this is only the surface, youkoso.