That's the problem. I think while the V40 has a a lot of nice features and it will be perfectly fine. I think the raw power of the 6T with the customizations Oxygen OS offers will make for a nice experience. Plus again, $140 price difference.
I've handled a 6T at my Tmo store and it is a nice piece of kit. You said in an earlier post that music was not that important to you so that negates the lack of headphone jack and DAC on the 6T.
An OS skin is a skin. Some of the skin features on my V40 I like, some I don't. I'm sure I would have the same experience with any skin. The real challenge is OS updates and the only way to get the fastest updates (without rooting) is a Pixel from Google. If you have a carrier phone, you will wait longer. How much longer will depend on the phone manufacturer AND the carrier.
Based on your lack of need for music and your discussions on pricing, it seems to me that the priority in your decision making process is cost. If this is correct, go with the 6T. If this is not correct, look at your priorities for a new phone and go with it.
If the 6T had a headphone jack, I would probably have gone for it. The window of holiday savings won't be open long.