Season 5 is my least favorite, actually. I still like it, and it has some great episodes (the one where Daryl and Carol go to Atlanta, or Tyreese's death episode) but the big arcs all felt underwhelming. The Terminus arc was resolved in 3 episodes. The first episode was a big display of shock & awe, but ironically in the end the only survivor we lost was Bob - and technically he died to the zombie bite.
The hospital arc almost felt like a standalone arc - it had no consequences. It once again showed that people become crazy in the zombie apocalypse. Yeah. But that's about it. Beth's death was unfitting, if anything it should've been Carol.
I did actually like the struggle for survival. Those 2-3 episodes felt deliciously depressing. And it was great seeing the group actually being together.
Alexandria was a very nice change of pace, but I have to say that the plan Rick was conspiring (hostile take-over) was far more interesting than what we got in the end - you know, some jackass randomly cutting Reg's throat open. It was just too much of a coincidence for me. Not to mention that I absolutely HATED what they've done to Sasha and Gabriel in the 2nd half. Their scenes just went nowhere. Constant anger, crying, breaking down. Yes, I understood the purpose, but to drag it out for the entire 2nd half? Thank god they actually became proper characters again in season 6.
Season 4 is my favorite season, because while it may have been slower, had less stuff going on, less deaths, everything felt more cohesive, and the payoff was always there.
The disease arc was a nice change of pace - after a whole season of fighting The Governor, and Shane before that, the show could really use a more "natural" villain - a virus. And it also provided an excellent opportunity to flesh Hershel's chaaracter out more. The show almost always puts the "badasses" in the forefront, but when it comes to fighting a disease, guns and muscles won't help you.
Then the Governor. In 2 episodes, he became far more compelling than he did in the entirity of season 3. He couldn't escape his true self, much like Rick. Yeah, he wanted to stay away from being a leader, from using guns, but it's just simply not possible. The clash between the Governor and the survivors is probably the most satisfying episode and payoff to a storyline to date.
The 2nd half was much slower paced, but it had some of the best writing of the show to date. Splitting up the group into tiny pieces allowed the writers to play around with their characters much more, and they made good use of that. Even the episode which is often considered to be the weakest of season 4(Beth and Daryl looking for alcohol) was intriguing, because, at this point you realized, this is season 4, these characters have been around for years, yet we barely actually know anything about them.
And after all that excellent development ,seeing them reunited in Terminus, no matter how dire the circumstances were... well, that was just phenomenal.