My order is 2>5>4>1>3
Episode 1 i thought was a perfect set up of the series, you got too see Lee and Clems really awkward conversations at the start and by the end you could see the bond growing. The other characters were introduced and you could pretty much decide who you were gonna like (Carley/Doug) and who you were going to hate (Larry). I think this episode is really underrated, after all it is the reason everyone continued to buy and play the season.
Episode 2 I personally thought was the most fun to play, and the one which i've probably played the most. I loved the St. Johns plot and thought it was genius, but i also really liked how you could see relationships you made in the first ep. had developed in the 3 months that had past.
Episode 3 i found to be my least fav, maybe because of the sheer fact that the group went down to so little in such a short amount of time. Eventhough it was to be expected, being the mid point of the season and all, but that doesn't mean you have to enjoy seeing your friends die! and where do i start with carley

no, i won't even go there actually!
Episode 4 i thought was a really good set up to the finale, but as a stand alone episode i wasn't the best, dont get me wrong i didnt dislike it, neither did i dislike ep 3 for that matter, but they just weren't hitting the heights of 2 and 5. I really liked molly as a character and was gutted she didn't make another appearance, especially after reading that she was confirmed to be in ep 5 :S
Episode 5....... wow, where to start, i dont even know how to explain this. end scene was the most powerful thing i think i have ever experienced, the way you can see how desperate clem is to not give up on you, when she says "you can lean on me if you want" i choked up and the tears started to flow, shes just so ADORABLE!! the ending i thought was perfectly written and beautifully preformed, and a fitting end for season 1.