Season rankings?

Worst to best
4
3
2
5
1

4: D+
5: C+
3: A
2: A
1: A+

From best to not so amazing:

Season 1: A+
Season 2: A
Season 3: A-
Season 4: B-
Season 5: B+ (was all worth it for the finale though, which was mostly an A)

1. Season 4 B-
2. Season 5 B+
3. Season 2 A
4. Season 3 A+
5. Season 1 A+

Worst to best? In my opinion:

Season 4 - B (the writting was pretty weak in this season)
Season 5 - B+ (definitely not the best, but still a good season)
Season 3 - A (was pretty slow in the beginning, but the final episodes were awesome)
Season 2 - A+ (masterpiece, with some of my favorite actors, like Tim Olyphant and William Hurt)
Season 1 - A+ (masterpiece, one of the best television seasons I've ever saw).

I agree with everyone that 1 was the best, and 4 the weakest. I still enjoyed 4 though - what a cast!

I enjoyed 2, 3 and 5 equally in retrospect.

Worst to best
4
2
3
1
5