I assume you mean Dinkelsbuhl. It is quite like Rothenburg so you might be repeating the experience. Wurzburg is a larger place, and has the Residence, which is worth a trip to see.

Dinkelsbuehl is only about 30 minutes from Rothenburg and it is south of Rothenburg, while Wurzburg is north (west).

I am not sure from whence you could be coming that it would be an either/or decision? If it is Frankfurt, then Wurzburg would be the better choice both logistically and for the reason adeben notes.

Dinklesbuhl is a miniature Rothenburg, so that would be an unnecessary duplication, or 1.1-ication

Wurzburg-Residenz-magnifique-dont miss

Tidy, perhaps nobody here has been kind enough to tell you about the real R-burg (so you can more easily decide if you want to see yet another "miniature" one.

Although the place is charming in many ways: the moat, the drawbridges, the overall look and feel of stepping back into the medieval world, the town is certainly NOT totally "medieval." There is plenty of quite modern commercial, shall we say, "enhancements." Such as those four (at last count) Christmas stores and a bunch of other "themed" totally revenue-generating establishments.

I think the place is wonderful given what has been preserved up to the present day and a lot of people are going to tell you that it is better than going to some "faked" Busch Gardens Old Country or Disney Fantasyland. But it is what it is and once you've seen it you might want to venture to some other towns which are still "old" but offer a different perspective.

In this case I think you'll be much happier visiting Wurzburg.

I don't see that the OP asked if anyone had a personal hate on for Rothenburg, but I am sure the "kindness" is appreciated.

Thank you, it sounds like the choice is Wurzburg.
Aramis, I will be coming from the south, spend a night in Rothenburg and then on towards Frankfurt; that is why either was a choice.