Originally Posted by CPH-Flyer

I have stayed at both.
Osaka Station Hotel has a better breakfast, service is probably same level (different style), some people will dislike the more funky rooms of the W, there are more food options at the Station Hotel without even leaving the hotel, W is a bit more central but as the stations are as close by, it probably does not matter, but transport wise, Osaka Station has more connections.

It is probably a toss up between the two.