N=1 but all of my friends use uber and none use Lyft. Not sure how long they'll last.
To be fair though, almost every Lyft driver I've had says they also drive for Uber, it just depends on demand. And consensus seems to be that out-of-towners use Uber while locals use Lyft.
Lyft has been an infinitely better experience for me, and I have the option to tip.
With Uber the price is either fixed also (SF), or there is a fare estimate button after you set your pickup location.