Post your new suggestions and try and flesh them out a little to give context and placement within the world.
Allow me to start with my suggestion - the Food guild/ Culinary guild.
Wait
Hear me out.
"How exciting could food be I hear you ask?"
Well take a scrap out of a show called Hunter X Hunter which has as you imagine "hunters" which are much in the same vain as adventurers in the fantasy genre. During a part of the hunter exam (where people must prove themselves to be the best of the best and get their license to take dangerous work) a part of the exam is handed over to food hunters which is laughed at by some entrees but it soon becomes clear that they could well be some of the most badass hunters out there. This is due to and what I would have the culinary guilds objective be is make the amazing and rare meals they can gathering all the essential ingredients, this doesn't sound to thrilling but consider what gathering "rare" ingredients would actually entail. Why has no one got these ingredients? Because they get themselves killed. Imagine a slaying rare bear deep within the mountains trapped by creatures keeping the meat to themselves, do you free the rest of the bears, take them to the guild for cultivation or take all the meat to the market? Imagine a herb that grows on the highest peaks that is guarded by a great dragon. Imagine a fish that only lives in a dwarves ruin deep in the ocean floor that you need another plant to expand your lung capacity (gillyweed Harry Potter nerds).
The possibility are endless and relatively easy to put together.
For my finale I would ideally have different branches of guilds in different cities like oblivion. After completing the quests of each guild you receive a letter from the guild saying the King (or whoever is the head honcho) requests the finest meals in the land for a special event. You are then tasked with choosing which branch to represent in preparing a meal for the King with each member taking a certain aspect which they will inevitably need help with. Shenanigans ensues with skullduggery, cheating, bribing and the sort to be the Kings own chef and finally you draw with whichever guild you annoyed the most with your actions in the contest astheking just can't decide and off you all go, no ones a winner. The most annoyed person with this result is not you or the other competitors but a daedric prince who was enjoying the show. You are transported to another plane with your team and the opposition and are told that a food contest to the death will take place. Whichever team wins goes home, the losers are cooked by the prince himself, the most illustrious honour. This strange place has flora and fauna no one has ever seen and therefore most be tried, potentially poisoning some team mates that require a antidote, perhaps offered to you by the prince if you can include an opposition team member in your ingredients. You win naturally and head home. Your deeds have promoted you to master chef (avoid that trademark perhaps) and now have the right to create your own dishes and name them in the same way spells could be created in oblivion, eventually you can see these meals appear in inns as they grow in popularity.
Side note the daedric prince finale if you wanted to really turn it on its head you could make it so that whoever WINS gets the honour of being eaten by him/her so both teams are desperately trying to lose and make it as awful as possible but at each course you give him seperated by ingredient collecting, he loves every dish he's given and both teams are freaking out until, a member of your team (or you) urinates in the dish in front of him essentially sacrificing themselves for the teams return but he is still positive on your dish however he declares he prefers tradition means of food delivery as he is not swayed by contemporary Presentation, preferring the flavour to do the talking so on a technicality declares your team the winner. Shocked the other teams captain urinates in the dish after the competition is over, the daedric prince calls him lude and uncultured saying art should not be replicated by amateurs and promptly vaporises him, returning you all back home whilst the other team is left to their doom.
Give me thoughts on my idea and suggest your own