They are 3 completely different movies in 3 completely different genres. You should have put movies that are similar together. Personally I love pulp fiction (And it will be the winner of this poll for sure) but shawshank has more thinking, more emotional thinking, than pulp fiction. The way that it makes you feel, think, and view prison is different.
Also, I recommend watching Felon. It's about a white guy who goes to prison and has to join the woods (A co-op gang with the aryan brotherhood) and it's more similar to pulp fiction (not quite the same genre though, pulp fiction has more humor). If anyone is like me and has and would beat someone half to death to protect or fend for a loved one would definitely relate. It wasn't a popular movie but everyone I've ever had watch it has loved it. It used to be on netflix but if you can download it or watch a trailer do it. It's a great great great movie.