From my own limited experience, I'd say the Planar is decisively sharper off-center, somewhat sharper in the center, and has a certain "pop" factor the Tessar types lack---but it might fairly be accused of a certain modern, "clinical" look that isn't always what you want. But neither one will ever, *ever*, be accused of being a technically inadequate lens, except by someone who's got something wrong with them!

We may lose sight of this aspect sometimes, inveterate gearheads that many of us are---it's easy to get caught up worrying about the difference between "really really good" and "technically better than practically anyone needs".