Basel vs. Strasbourg - one night before flying to AMS

Both cities are very safe. Strasbourg has more to see and visit, including an incredible Cathedral, a very well regarded Christmas Market, charming canals, half timber houses.

Whereas Basel, while it has a pleasant old town, is overall much more modern, with a lot of uninspiring concrete. Good museums though, it seems, but I'm not much of a museum person so I haven't visited any there. I don't know about the quality of the Christmas Market there.
Also, whatever you save on hotel room will be lost on expensive food (it's difficult to eat anything non-fast food for less than $30).

Airport transfers aren't a differentiating factor (very frequent bus in Basel, very fast and quite frequent train in Strasbourg)

So my preference is Strasbourg. But Basel isn't bad, if you want a taste of a different country.

How are you travelling from Paris to Colmar? If by train, you would most likely go through Strasbourg and could take some time to explore - or even stay the night - before continuing on to Colmar which is a relatively short train ride. After Colmar, you could continue on to Basel. Seems you could see Strasbourg, Colmar, and Basel.

Thanks for your suggestion as it is a good one...
Unfortunately, my dates are locked as I am meeting a friend for the 3 nights in Colmar.
I only have two full days to explore the villages around Colmar so I doubt we will have time to visit Strasbourg (while in Colmar) as I have a full agenda (Hoping to visit Eguisheim Christmas Market, Marche de Noel Kayserberg and Riquewihr).

The flight from Basel will lands in AMS at 1 PM (daylight in November)
The flight from Strasbourg lands at 4 PM (quickly getting dark in November)

I have been to AMS before, but I feel like it might be more intimidating to arrive at dusk... But I also don't want to miss the chance to visit Strasbourg.
Thanks again for your advice!

Itinerary
2 N Paris
3 N Colmar
1 N Basel or Strasbourg
2 N AMS

Logistically I think Basel makes more sense... It is less expensive and the flight time is slightly better, but Strasbourg seems like a city that I don't want to miss. Which would you choose?

With the additional elements you provide, I reinforce my vote for Strasbourg! From a sightseeing and Christmas Market standpoint there's no contest. Basel's Muenster is no match for Strasbourg Cathedral, and the bend of the Rhine doesn't match the charm of Strasbourg's canals.
Logistically they're equivalent, since a night-time arrival in Amsterdam isn't what I'd consider intimidating.

A regular poster on here lives in Basel, so maybe they'll chip in.

Thank you to all who replied!
I sincerely appreciate your advice. I decided to go with Strasbourg as the charming architecture was irresistible to me (and I think I might prefer the Alsatian cuisine a bit more - I'm excited to try a tarte flambée ;-)