I think you're looking for a good Wintergreen.
The only one I've tried so far was from Vapor4Life.
I think that fits the bill you describe, except it's not mentholated, but you can
buy menthol separately.
It is, however, a fairly good sweet mint flavor.
You may find that you don't need to mentholize it when you try it, but if you want to, you can do that separately.
Honestly, I have found that menthol actually can decrease flavor and can kill a good
juice flavor unless it's used with the correct flavor in the correct amount.
I like the sweet mint flavor too, and want to try more vendor's Wintergreen flavors.
I ordered a 30ml from V4L, and it's almost empty now, and will probably order another one.
It is one of my most-used juices, I use it to flavor a lot of other juices besides
vaping it by itself too.
I actually use it to 'sort of' mentholize other flavors, but it's not a true menthol.
True menthol doesn't have any real flavor, this does.
I ordered some Spearmint just the other day, curious if it will be anywhere close to the sweet mint Wintergreen flavor.