I started this series with the 4th game and it was fantastic.

Going back to 3 I noticed how improved 4 was however I've got to say I enjoyed the locations and missions more in 3 at the time of finishing.

I may have to go back and play 4 as I do prefer 4 overall but 3 was really a special game the story was kinda whatever but the locations music and gameplay were all really fun.