This is a matter of preference.
Studio One will give you all the features you need in terms of recording.
When Studio One launches with the Studio 192 running, the mixer interface in Universal Control is bypassed and all I/O is managed by Studio One.
Studio 68 does not have the extensive control panel that Studio 192 has, yet if you're going to do everything in Studio One, then you may not need all the features of the 192.
It basically boils down to how many inputs do you need at one time.
If budget is a concern, then go with the Studio 68, it will give you the best value for your money.