Abeno Harukas or Umeda Sky Building?

Hi,
I planned to stay in Osaka for two night.
I still have one night to spare to go up to one of this building.
Which one do you recommend to take?
I know that Abeno is newer and nearly twice as tall, so the view must be broader, in exchange to twice the entry price.
Mean while, Umeda has more unique design, more renowned, and has open air rooftop.
Other than this, is there any other reason to think of?

Thanks a lot

If you can, go to both. The views from each are quite distinct from each other and both are well worth it. You have already named some of the differing characteristics.

For Umeda:
https://www.youtube.com/watch?v=xb1wuyAGgyQ

Costs less than half the Abeno ticket. And yes, you get the rooftop view - no glass partition - nothing but a light breeze between you and the Osaka skyline. Can't beat that. Also has more variety as far as the view goes - with the river on one side, and skyscrapers on the other. It's also open a bit later than Abeno.
On the more negative side, it takes about 10 minutes on foot from the station. No big deal, if you are traveling through Japan though.

For Abeno Harukas
https://www.youtube.com/watch?v=-AyUZmGbW8g

Much pricier, but it's the tallest building in the area -- you're on the 60th Floor instead of the 40th, and you can see 50km away if the weather allows. It's also right next to Tennoji Station. The view is almost like being in outer space at night. There is an open roof, but only towards the sky. Has a trippy elevator ride up as well, plus a moderately amusing projection light show on the floor.

Of course, the Abeno Harukas has a hotel in it that is just below the observation floors. The rooms are not cheap - but not as bad as you might expect. You could get a room there, go to the Umeda Sky Bldg, then enjoy the Abeno view from your room all day and night long.