Impossible as the question makes absolutely no sense.

Pros and Cons of 2 things you can only compare if you talk about the same thing, but ...

USB you use to connect a recording interface to a computer. In the RME world this can be either USB2 or USB3.

SPDIF is one of the many I/O channels of a recording interface. It can be optical SPDIF or koaxial.

So these things serve completely different purposes.

Please more details and what you really want to know .... you are about to do ...

What general recommendation in what regards ?

1st of all you can connect an audio interface only by
- PCI / PCIe
- USB2/3
- Firewire 400/800
- Thunderbolt

Which of these technologies is present in RME products depend on the product requirements, i.e. how many audio channels have to be transferred between audio interface and the computer. Or whether its for Desktop PCs or if you need smth for a laptop.

But what shall I tell you something about the shiney world of thunderbolt recording interfaces, if your machine does not support thunderbolt and if €2700 for an UFX+ overstress your budget.

It would make much more sense if you would describe your current setup. How do you record currently. What PC do you have (CPU, mainboard), where you feel limited. In what way you want to improve your setup. Whether you cant use i.e. a PCI/PCIe based interface as you require mobility by laptop, etc etc
How many analog and digital ports do you require IN/OUT ... depending on what you need to connect.
Does your interface require stand-alone capabilites ... etc etc

You need to tell something about your budget, goals, surrounding conditions, otherwise this whole discussion makes absolutely no sense at all.

You make it even harder by not telling explicitely, whether you have or intend to buy an RME product, so that you require help for a good purchase decision or whether you simply have no clue about a certain topic. But as I said, even your question alone makes without any additional information absolutely no sense.