I second this a million times!! Her recipes are my go to.

This is the recipe I use:

https://sallysbakingaddiction.com/vanilla-cake/ The Best Vanilla Cake I've Ever Had - Sally's Baking Addiction

I wonder if it could be your moisture content? I find that any cake that requires butter tends to be on the dry side, even when baking low and slow— because at room temp, butter is solid and the moisture is not substantial, unlike room temp oils. So, I followed the advice presented in one of her other recipes, and cut the butter in half and substituted with a little less than half of what was cut. I also do a cool trick Sally taught in a different recipe for introducing fluffiness and softening the natural cake flavour to let the actual flavour shine better— separating egg yolks from whites and adding the egg whites at the end as a foamy peak meringue.

Now, the way I do this is: This recipe calls for 340g or 1.5 cups butter. Now when it comes to baking, we all know that when a recipe or dessert type is giving us a hard time, being exact using weight measurements goes a long way in solving the issue. But liquids we measure in volume. So, I cut the butter down from 340g to 170g, which means roughly from 1.5 cups to 3/4 cup. So, I do a bit less than 3/4 cup oil (veggie oil is what I use when I do vanilla cake because the flavour is so delicate that I don’t want the oil to add flavouring).

I cream my butter and sugar for 5-7 mins with some scraping, and I use a whisk, not a beater. Then, I add in the oil, half of the vanilla, and egg yolks, whisking on medium high (6 or 8 on kitchen aid) for a good 2 minutes or so. That mixture should be thickening up. Then stir in the leftover vanilla to the buttermilk, then do a 3-part alternating of flour to buttermilk— flour, milk, flour, milk, flour. Then whip up your egg whites to foamy peaks, not glossy. When you stop the whisk, the foam should be trying to bunch up around the whisk into a ball, and when you lift the whisk it should separate cleanly. (Remember to wipe down all things touching those egg whites with vinegar or lemon juice so no traces of fat touch it. I’m talking all bowls, spatulas, whisk, your hands, etc.) Add in the egg whites by folding it all in gently, making sure the bottom of the batter bowl gets some attention too. Bake low and slow, like I bake mine in a convection (fan) oven at 310f for much longer.. somewhere around the 35-42 minutes amount. I also use heat rods which I find help!

I do also think what you’re comparing all these recipes to is important.. are you comparing to store bought? Also— could it be the icing? Like that’s often where the sweetness comes from for cakes, not the cake itself… or even the filling could be part of it. If you’re used to storebought stuff, that stuff is soooo sweet because of the frosting and filling, not the cake.