I have only ever been to France and Lanzarote. I generally like Lanzarote, but the second time I went, I was 13 and pretty caught up in puberty so I couldn't really enjoy it. I didn't enjoy holidays at that age. Cornwall, and the last 2 times I went to Lanzarote I all remember as being boring and I just wanted to go home, but that was due to be being an antisocial p*ssy at that age. I'm really disappointed in myself for not being more willing to try new things at that age because I know if I went to either of those places now I'd like it. I recently went on holiday to Devon (which was also my first holiday without my parents) with a mate and I absolutely loved it, so I think I'd feel the same about Cornwall now considering it's fairly similar. I'd also enjoy Lanzarote now because weirdly enough Devon is actually somewhat similar, if not a bit more humid and wet.
I don't think it helped that the last 2 times we went to Lanzarote, we basically didn't do anything. We did all of the tourist attractions the first time I went when I was 9 (and I very much enjoyed it that time), so there wasn't anything to do. So I think I got bored of it fairly quickly. I'm the complete opposite of what I used to be, I love going to different places now.