I had a really pleasant stay at City Plaza Osaka. The location is not right in the middle of the main tourist areas, but it’s also not too far — around 25–30 minutes by train to most popular spots. The nearest station is Sakaisuji-Hommachi, and it takes about 8 minutes to walk from the station to the hotel.
One important tip if you’re coming straight from the airport with luggage: use Exit 15 at Sakaisuji-Hommachi Station. There is an escalator there, which makes things much easier with suitcases. Google Maps may direct you to Exit 12, but that exit has a long flight of stairs and carrying luggage up there is honestly quite a struggle!
The main reason I booked this hotel was because of the onsen, and it definitely did not disappoint. After spending the whole day walking around Osaka, being able to come back and relax in the onsen was absolutely worth it. The onsen was one of the highlights of my stay and I would happily stay here again because of it.