I'm building up my first NEW frame for myself (a Rawland 650B all-rounder), and I'm using a mix of mostly NEW and just a few vintage parts. I'm trying very hard to choose each piece strictly based on functionality/purpose, but sometimes aesthetics just has to trump when two modern parts that are roughly equivalent happen to differ mostly in the appearance department.
Case in point, I'm going with a previous-generation Shimano 10-spd RD, the Dura Ace 7800, which, IMO, is pretty:
Its successor, the current Dura Ace 7900, also a 10-spd RD, will do roughly the same job and weigh just a few grams lighter, but is Budd-Tuggly if you ask me:
While we're at it, I was also pondering a modern Campagnolo of Shimano drivetrain, but in the end decided to go with a modern Shimano drivetrain but vintage TA crankset which would give me a lot more versatility (and barely any weight penalty). Here's the current top of the line Campagnolo crankset offering (pretty):
And here's the current top of the line Shimano offering (ugly):
And a 40-year old TA crankset (which I'm going to use with a modern Phil Ti BB). I think this trumps all the new crankset offerings in both function and aesthetics, and will blend nicely with the modern polished alloy Shimano RD: