While I hesitate to give the Avengers too much praise, the final action scene in that film was really well done, for what it was. It was built up well for most of the film. Instead of it being two supermen fighting and not caring about the massive amounts of collateral damage, it was a half dozen heroes that had to work together, each offering some unique way to contribute talents. It also was bright and colorful and really looked and felt like a comic book. There was a progression to the fight. Each character got involved in their own unique way, an eventually they had to figure out how to deal with the threat. Man of Steel's fight seemed long, tedious, repetitive, humorless, boring, shallow, preachy and all of that. As well as dull, and colorless, and it felt like the stakes were less important than its own showiness. The Avengers took time to save people from what was happening. Superman in the original films spent more time saving people than actually engaging Zod and his cronies. Man of Steel's fight seemed, endless, excessive, and utterly pointless. That's why the minutes dragged and dragged, because it was all listless and there was nothing to hook the audience after the initial minute or two of seeing two Supermen duking it out.
The biggest difference between MOS and Avengers is what the focus is.
MOS focus is on Superman facing a challenge (on screen at least) bigger than he has ever faced before. Zod and his followers were fully complacent with wiping out humanity and colonizing Earth. We cheer for Superman because he is facing such adversity and is overmatched. In previous movies (Superman II) he fought Superbeings as well. However they mixed their attacks with standing on buildings, posturing and expositing dialogue. The villains of MOS are hardpressed to cause as much physical harm to Superman and everyone in their way. In the end Superman was able to save the planet. That's all that should matter.
The focus of Avengers is the gathering of the Avengers. The big 30 minute action scene at the end was just something to bring them all together. The assembling of the Avengers and their interactions is all that matters. It's why the threat in Avengers isn't that important and is essentially a fodder army there to give the Avengers something to hit in the finale. There are 2 scenes of the Avengers rescuing people: Hawkeye and Capt rescuing people in a bus, and Capt by himself rescuing people in a bank.
I'm not sure we can adequately compare the action scenes in Avengers and MOS in that regard. Since both films are trying to accomplish different things with their respective stories.
I complied every action scene in both movies. Judge for yourself.
Action scene length in Avengers:
The Intro: Beginning with Loki shooting his first bolt from his staff and ending with Fury saying "We are at war" is roughly
6 minutes.
Loki, Capt. America and Iron Man in Germany - roughly
4 minutes including dialogue from the moment Loki strikes that guy with a cane.
Iron Man vs Thor on the mountain: About
3:30 minutes. From the time Iron Man tackles Thor to Thor, Cap and Iron Man standing together and the "Are we done here" line.
The fight on the Helicarrier: Beginning when Hawkeye destroys the first turbine to Nick Fury running up to Agent Coulson it's about
14 minutes.
The Battle of New York: Beginning when Iron Man engaging the Chitauri and ending when Hulk catches Iron Man is about
26 minutes.
Action scene length in MOS:
On Krytpon: Starting with Jor-El escaping his guards and arriving home is about
4 minutes.
On Krypton: Jor-El vs Zod and his two guards and ending with Kal-El's ship warping away is about
2:30 minutes.
Superman rescuing the people on the oil tanker takes a little over a
minute and 20 seconds.
Superman learning to fly sequence is roughly
2 minutes.
Lois Lane shooting her way through the ship and Superman rescuing her (including dialogue from Jor-El to Lois and Kal) is just under
4 minutes.
The Smallville Battle between Supes,Nam-Ek, Faora takes
6 minutes.
The World Engine pulse and Superman attempting to stop it takes roughly
10 mintues.
Superman destroying the scout ship and Faora attacking the B37 before being pulled into the phantom zone takes a little over
2 minutes.
The final fight between Zod and Supes, takes
6 minutes. Beginning when Zod tackles Supes.