With a larger case you can get both Pam's and Data, but either way, get Pam's first (or at the same time). It's really useful and usable. Data has a lot of added features, but you can only use one of them at a time (with the exception of fixed voltages, which you can use with other modes). So if you're using it as a clock, you have to stop doing that to use the oscilloscope, and then what you want to look at might be gone.
Quadrax is a newer version of Quadra and is also very useful, though it takes some study to grasp the added features. You can pretty much use it like Quadra soon after installation, ignoring the more complicated stuff. That's also true for a more complicated oscillator (and I don't think Dixie II+ is much more complicated than STO). You don't have to use FM or flip sync until you want to. (And Data helps when you do.)