Oslo, Stockholm, or Gothenburg?

Last night myself and a couple friends booked our plane tickets to the Scandanvian area! We have a "free day" so to speak budgeted into our trip. In our past adventures we've spent that free day exploring a random city. Due to the locations of the parks that we're going to visit we have the option to use our free day in any of the cities listed, Oslo, Stockholm or Gothenburg. I do plan on trying to see a bit of the other two but my question is which city is worth spending an entire day in? Not looking for anything in particular as I really don't know much about any of the cities listed other than the wonderful music they produce. Just random touristy things to see. Thanks!

I would go for Stockholm, very beautiful city!

I would also cast my vote for Stockholm.

Stockholm.

Home of The ABBA Museum!

There's also, I remember, a small ferry system that takes you

all around the city's harbor/inlet with stops at other tourist spots.

Including Grona Lund.

Grona Lund! Part of the Stockholm harborside. (o:

There it is! And to the (sort of) left of this, and on the other side of the street, is.....

There is a HUGE ship (Colonial? Viking?) being restored over here, beyond ABBA,

but I didn't give myself time to see it. Or to walk waaay over to it, too. )o:

Looks like it'll be Stockholm then!

Not really into the ABBA museum though but Grona Lund is of course in the plans! Anything else anyone recommends a couple US tourists dedicate part of their day to? Any obscure Swedish things that anyone would find pretty cool?

^ All I know, is some of the stuff in the area around Grona Lund.

And that ferry system that travels around that harbour area.

What ever you decide to do, have a great visit there!

I have never been to the two others, but Stockholm is very nice.