I voted for the hero's quest games (Sure hope it was also quest for glory, I think it had 2 names).
I liked the way there were multiple ways to solve a puzzle in the game. You had all these "sub-quests" you could take if you wanted to to earn money. I especially had great fun with the first game in the series making money and then buying a spell which would allow me to (Hopefully) gain more money. Of course I didn't complete everything in the game, I skipped a few things, but I really liked the way you had multiple answers to puzzles which allowed you to complete the game in another way if you didn't know the best way. Only completed the first game though.
As for LSL, well I bought the compilation (PC) because of some distant memory of the game. I didn't really like it as much as I liked the hero's quest games. As for LSL 2. I never made it to the island because I never got off the boat. Every time I would try to leave I would end up in that darn raft and dry up in no time. I figure I'd need some sun-block and also think I might have found it in the barber's shop, but I just didn't know the word to look for and thus never got it.
I think Space quest has a funny concept, unfortunately I never played other games in the series than 4 and 6. Both were really hard and I haven't played far in either of them.
With my version of SQ4 there was a solution to the first part of the game, but no matter how close I followed the instructions I always ended up getting shot anyway. He just wouldn't hide and wait.