As far as bran muffins, I used to like this recipe: https://www.cookiemadness.net/2010/05/14/favorite-bran-muffin/
But for now, my favorite bran muffin is hands down the Tortino di crusca (blackberry bran muffin) in Jim Lahey’s The Sullivan Street Bakery Cookbook. In fact, it could possibly be my favorite muffin at the moment, period. Sorry, I can’t find the recipe online.
As far as pumpkin muffins, you can use this gently spiced Pumpkin Bread recipe (see notes for muffin instructions) from Smitten Kitchen: https://smittenkitchen.com/2016/10/pumpkin-bread/
If you want, you can read about my quest to figure out if it’s the spice that defines pumpkin bread (currently I am using no spices): https://www.chowhound.com/post/baking-days-october-2018-edition-1076561?commentId=10140171
I never tried those muffins in real life, but I’ve made quite a few of the copycat recipes. I commented on it a while back: Tracking down a baker who used to work at Greig Farm in Red Hook, NY - #5 by bmorecupcake
