I'm a grape junkie. It's my primary vape. Grape bubblegum actually. I have tried all the grape flavorings from all the major flavoring manufacturers as well as VZ and other comprehensive vapor shops. Many vapor shops repackage and relabel the flavorings they sell. So, other than VZ, you are unlikely to find flavoring other than that produced by one of the major manufactures.
I have tried FA, FW, NF, TFA, FF, TP and LorAnn. All were poured down the drain. The only 2 acceptable grape flavorings I have found are VZ grape and Capella's. Capella's concord grape is the best as far as I am concerned. VZ is a close second, but it is alcohol based. I find it easily overpowered by slight amounts of other flavors, even mixed as high as 30%.
Additionally, I have tried many ready mixed grape liquids. All, including Ahlusion's grape vine are made with one of the flavorings I poured down the drain. I have 60ml of grapevine and 50ml of MBV grape sitting untouched. I have poured others down the drain, but can't yet accept my wastefulness on those two large bottles. The only ready mix grape I liked was Pink Spot's grape hubba bubba. However, I had to tweek it.
As a result, I have been experimenting. My best grape bubble gum so far is as follows:
30ml batch @ 12mg/ml with no PG other than what is contained in the flavoring.
7ml Capella's concord grape
2ml VZ grape
0.5ml Tasty Puff ghetto grape
1.5ml Capella Bubble gum
8 drops EZ Sweetz (liquid sucralose)
VG nic base
With either ready mix or homemade, I can never get the flavor strong enough. I would vape pure flavoring if I could. If the OP or anyone comes up with a good grape recipe, let me know. I'm will sample just about anything but will not buy a pre-mixed grape. I won't be fooled again.