DXO? Besides you, who uses DXO?
At the moment I'm using both DXO and Photoshop.
I have been using Photoshop on and off for a long time.
I use DXO for Prime noise reduction. In addition to to DXO Optics Pro, I have Viewpoint 2.
I can get a decent image out of DXO directly, but more likely than not, unless it's a snapshot, it'll be sent over to PS for more work.
With more than one software package, you can take the same raw file into each to see which you prefer.
For lens correction profiles, Canon does Canon, but DXO and PS [ACR] support a range of manufacturers including some camera phones.
I do not like the Adobe subscription model. I prefer the DXO model - perpetual license, then upgrade if the newer version looks worth it.
Beyond money, more than one software package takes time and energy. You can be completely deep with one package or less deep with several. I haven't done a lot with Gimp -- I'd need to learn new workflows. The ones I use with PS are adequate right now and will remain that way unless Adobe starts charging more than they are worth.
I'm not sure which one I'd keep, if I had to keep only one.