I am on a vanilla quest as we speak... The best thing I can think of to get a real vanilla vape is to pick up a small amount of vanilla absolute and make your own flavouring.
With the TPA flavours, I have found that 6% bavarian cream, 4% french vanilla, 1% caramel 2% ethyl maltol is a nice vanilla vape. Too much of the french vanilla gives a weird taste I find... no more than 5% (even on its own)
I have a whole bunch of vanillas (both DIY flavourings and premade juice) on the way that I am going to dig into when I get back from mexico (feb 5th or so). Stay tuned to my vanilla thread in the general e liquid forum for updates on my quest.
Cheers!