What are the most important factors for you?
Footprint?
Playability?
Portability?
Other?
Do you care about included sounds? Your opening post suggests that is not particularly important.
My situation was similar. I have plenty of drum/percussion VSTi's, so I wanted just control.
Btw, your Oxygen 49 is ideal for percussion such as Tablas, congos, etc. Most of these are mapped to the keys so that subtle variations are very easy and satisfying by playing the keyboard.
Even though I have dedicated drum controllers, I prefer the keyboard for these types of drums.
That said, there is nothing like playing drums when you want to play drums.
So I went with this:
Yes, I know you specified pads, and a kit may be too large for your space.
But the units you have mentioned cover a broad price range, and there are kits that fall close to that range.
The Alesis Control Pad at the top of the picture would be my most direct answer to your question.
With the small pads on most of those controllers, you are still doing tabletop drumming, and to me, you don't gain much over what you can do with the keyboard.
On the other hand, the pads on the Control Pad are large enough to play with sticks, but it is still a fairly compact unit.
What I really like is that each pad can be mapped to a different channel.
So I can assign the pads to 8 different synths if I choose to do so.
It is not currently in production from Alesis, but you can find it on ebay for less than $100.
May or may not be the direction you want to go, but my 2c.