Both Buffy the Vampire Slayer feature an ancient group designed to collect knowledge about supernatural entities and discover ways that these entities can be fought. The two groups try, in their own ways, to protect the world. In Supernatural, there is the Men of Letters, composed of men (and some women). Sam and Dean find out that they were meant to be Men of Letters as was John, their father.
In Buffy the Vampire Slayer, Giles is a watcher, meant to help Buffy in her work. The Watchers Council is meant to him and Buffy. However, that is not always the case, and Giles and Buffy reject the Watchers Council for a time. It could seem that the Men of Letters is better than the Watchers Council, but in other ways, they are not.
Better: Can Time Travel
In Season 8, Sam and Dean meet Henry, their grandfather. Henry is John's father, a person who had abandoned a young John. Later, Sam and Dean realize that Henry had merely gotten stuck in their world and had never intended on abandoning John. Both Sam and Dean are mystified that Henry could time travel. However, for Henry, this is a simple spell in which many Men of Letters would know.
He tapped into his own soul's energy to do a blood sigil, leading him to his closest blood relative. Mystified, Sam looks on, stating that he thought only angels could tap into a soul's energy.
Not Better: Have Disdain for Hunters
The Watchers Council works closely with a hunter--the vampire-slayer. They send a watcher to help her hone the skills necessary to fight vampires and other supernatural beings. As a group, they may leave some important details out in what information they share, but they do respect the slayer. The balance and salvation of their world depends on it.
The Men of Letters think of hunters as apes. Henry says as much as he time-travels to meet his grandchildren. When viewers meet the British Men of Letters, they also have disdain for hunters, especially American hunters. They start to believe that having no hunters in America is better than having any hunters.
Better: Created Bunkers
The Men of Letters created safe places for their in the form of bunkers. These bunkers are warded against evil beings, hence protecting all those inside. In addition, they house magical artifacts and books about the supernatural. For Sam and Dean, all of this knowledge gives them an advantage in their work. Additionally, it also gives them a safe place, a home.
The Watchers Council didn't have bunkers. Matter-of-fact, Buffy fans don't really know where all the watchers in the Watcher Council were housed. It's suggested that the watchers were more spread out.
Not Better: Didn't Train the Hunters
The Watchers Council is very invested in the slayer, sending a watcher to help train her. The watcher trains the slayer in many ways from helping the slayer fine-tune her fighting skills to teaching the slayer essential knowledge about her foes. The watcher assigned to the slayer often gets so invested that the slayer becomes like family.
The Men of Letters traditionally was quite separate from hunters. Sure, as Henry said, they provided information to a few trusted hunters, but that was about it.
Better: Kept a Thorough Archive
Sam is in heaven when he finds the archive of the Men of Letters. Although the American Men of Letters appears defunct, the knowledge has been stored and kept safe. Up until this point, Sam and Dean had been relying on their father's journal for information about monsters. Then they relied on Bobby. Now, they have a library of knowledge.
The Watchers Council is so secretive in that they seem to limit who has access to what knowledge even while watchers are being active in the field. It's a hierarchy.
Not Better: Limited Roles for Women
It's all in the title: Men of Letters. Henry even explains how the Men of Letters role was ed down to him from the men in the family--his father, his grandfather, etc. Still, strangely enough, there seem to be more roles for women than there are in Watchers Council on Buffy the Vampire Slayer. A couple of those women (i.e. Lady Bevell and Ms. Watt) attained leadership roles.
Still, they are a few in an ocean of many Men of Letters. On top of this, traditional roles and limitations were furthered imposed in ways as complicated as the original Watchers Council forcing the First Slayer to become less-than-human in order to protect others. The Men of Letters convinced a Wood Nymph to trade her forest for their bunker and to mother them by cleaning up after them. While handy to have help when you are hunting monsters, it's a little demeaning to have an all-powerful wood nymph leave her forest to do laundry and make cakes.
Better: Kept Alive in Families, Family Ownership of Role
Sam and Dean are legacies in the Men of Letter as are many of the . This creates a sense of alliance and pride in the work, a sense of commitment that goes behind it just being a job. While it's suggested that some of the aren't legacies, many are or become that way.
Because Sam and Dean are legacies, they are able to have access to the materials and knowledge of the Men of Letters. This both keeps the organization alive as well as helps fuel their desire to follow the mission. In Buffy the Vampire Slayer, the Watchers Council may have a few watchers who are family (like Wes and his dad), but largely it's composed of people who came to it based on their own experiences.
Not Better: Limited Collective and Shared Knowledge of Magic
While it's true that Henry had knowledge of spells and it's suggested that there was a spell class, the extent that the Men of Letters seem to have access or knowledge of magic is more diminished than Buffy's Watchers Council. The Watchers Council has several who dabbled in magic before they were watchers, and it also has s that have magical know-how. Giles, for instance, has s with covens, and it's because of them that he's able to help Willow after she returns from being Dark Willow.
Even the British Men of Letters seemed less inclined to use magic, rather than force and violence. With the American Men of Letters, it's suggested that the magical knowledge was simply lost over time.
Better: Systematically Defeat Monsters
When the bunker is working at full capacity (enhanced by the wood-nymph's power), there is a radar that points out where certain monsters are. Cue Sam and Dean realizing that their hunter lives could have been much easier as they rush off to work and kill monsters. The British Men of Letters also has advanced technology to kill monsters. Initially, both Mary and Sam are interested in the British Men of Letters due to these technological advances and the systematic plan to defeat monsters.
For the Watchers Council in Buffy, they provide information to Buffy or the slayer to defeat monsters and protect the world. Their role is meant to be one of less action; after all, they are supposed to watch, not act.
Not Better: Limited Network
The Men of Letters come across as very siloed; branches aren't in regular with each other. If they were, then the British Men of Letters would have known more about the American Men of Letters and the legacy families. Also, if they were more connected, then the British Men of Letters would have tried to save or help the American Men of Letters. Instead, each group stayed siloed.
The Watchers Council may be many things, but siloed is one thing that they are not. This is large worldwide network that's connected. True, the Watchers Council is also a little rigid in their beliefs, but eventually, they do listen to the Slayer and in the end, they are willing to be restructured by Buffy and her friends.