Besides the different number of channels, both interfaces also have a different feature set.

The Babyface Pro FS also has mobility in mind and is the only interface that can be powered via the USB2 port (or with the optionally available power supply).

The UCX II has many additional features such as a complete implementation of the FX chip, Autoset, DURec and has the preamp section of the flagship interface UFX II with 75 dB gain range (with some minor differences, see specs).
This can be useful in recording situations with a not so sensitive dynamic microphone.

Even if you are a beginner in recording, I wouldn't say it's overkill to choose the UCX II over the BBF Pro FS because the UCX II really offers very useful features.
DURec offers the security of a backup recording parallel to the DAW recording, so that nothing is lost even if the PC/DAW hangs.
And in the stand-alone mode, you can use the UCX II like a tape deck and import the tracks later in the DAW.

On the other hand, the Babyface Pro FS already offers a superb quality that is completely sufficient. You just have to think about what it's worth to you.
In any case, the UCX II is an excellent alternative to the two flagship interfaces and can already do a lot.

An expandability of the solution might also be desired at some point. Then, for example, you could always integrate additional mic or line ports via ADAT and still have the AES port free to integrate the ADI-2 DAC or Pro reference converter.

Buying too small is not worth it, either. I like to plan with reserves, on the long run you can also save money, and you have more possibilities from the beginning = higher fun factor.

You can compare the USB/FW/TB recording interfaces using the Excel from my Blog:
https://www.tonstudio-forum.de/blog/Ent … B-MADIfac/
Direct Link to Excel: https://www.tonstudio-forum.de/attachme … 4-08-xlsx/

For USB/FW/TB based interfaces these:

UFX     (30 ch. I/O, USB2, FW400) 2010 - 2016, out of production

UFX+ (94ch I/O, TB, USB3/2, MADI), 2016 - now
UFX II  (+) (30 ch. I/O, USB2), 2016, 2017 - now

(+) UFX II is the same as UFX+ but without MADI and without USB3/TB (for 30ch USB2 is sufficient)

You find them all in the above mentioned Excel.

The quality of A/D and D/A converters is generally quite high these days. I would focus more on what connectivity/expansion options and features you need.

RME doesn't have any special “house sound”. The devices are designed to record and play back audio unaltered in high quality. The sound is characterized as “transparent” not coloring, which is good, nothing should be added to the sound.
A few dB SNR more reduce the noise measurable, but these are all no criteria that have a direct or audible influence on the sound during playback.

It is not so much the AD/DA converter itself that is responsible for the playback quality, it is the combination of the converter and the analog amplification stage behind the converter.

I'm a bit surprised how you now specifically come to the MADIface XT. This recording interface has a special position because of the very high number of channels through the three MADI busses, so you can connect plenty of devices via MADI. But do you need this feature?

Then take a look at the UFX II, which was released a few years later, is even a bit cheaper and offers some advantages: higher number of I/O ports, which can be used directly. In 2017, there were also faster converters available on the market for the design of this product, which is always good for monitoring or routing on the audio interface.
The microphone inputs can even be used as instrument inputs (Hi-Z). The microphone inputs also have a higher gain range. You have features like Autoset and DURec. You can also connect the recording interface via USB2, which is available on all computers and in contrast to USB3 even allows cable lengths up to 5 m, which allows you to position the recording interface and computer more flexibly. The UFX II also has a built-in Real-Time Clock, so that DURec recordings directly to disk or USB stick always have a correct time stamp.

In your case, I would look at the features and see that the solution is still in a well manageable range for you also from price perspective.

I would concentrate the USB interface selection on the following products: Babyface Pro FS, UCX II, UFX II.

Furthermore, an excellent solution is the combination of recording interface and the reference converter, for example UCX II and ADI-2 Pro FS R BE. This would give you plenty of possibilities and also very nice features for monitoring via monitors or headphones, see these two blog articles that I wrote regarding this topic, which provide you more information.
You can add the ADI-2 Pro through AES and then you have still 1x ADAT I/O left to add e.g., more preamps later, if needed.

https://www.tonstudio-forum.de/blog/Ent … our-Setup/
https://www.tonstudio-forum.de/blog/Ent … ses-EN-DE/

So … If you do not require the many I/O channels of UFX II or UFX+, then save a little money by considering the purchase of the UCX II to get already excellent quality. Then I guess the chances are higher that some money is left, to add the ADI-2 Pro now or in the near future.

I am using a combination of
— UFX+, ADI-2 Pro FS R BE in the recording corner and 12Mic, Octamic XTC for mobile recording applications
— ADI-2 Pro FS R BE in the HiFi Corner, where the 2nd ADI-2 Pro is connected to the UFX+ through ADAT. Then I can record from HiFi or TV and use the PC as Music Player.