The Wire in particular is easy because each Season focuses on some different sector of Baltimore society, plus the characters roles switch in importance.
That's true. Actually, I do know for sure which season I liked best in that show - season 2, which, for some reason on IMDB, seemed to be many people's least favorite season.
But The Sopranos or Breaking Bad, I could not begin to rate the seasons.
1. Breaking Bad, Season 5
2. Dexter, Season 2
3. Breaking Bad, Season 3
4. Breaking Bad, Season 4
5. The Shield, Season 1
6. Dexter, Season 1
7. Boardwalk Empire, Season 3
8. Dexter, Season 4
9. The Wire, Season 3
10. Boardwalk Empire, Season 1
I know Flying Circus would be #1, and Twilight Zone would be in the top five or so, but that's about it. Too complicated for me to do without losing interest.