There are no reliable statistics on which to base choices of university/course. Absolutely none. The Unistats figures are submitted in different ways by different universities and are not directly comparable. League-table figures on staff-student ratios, spend per student, etc. are entirely made-up
Reading parts of this thread reminds me of the endless, obsessive questioning I get from some students about the details of an assessment. They focus on trying to get me to say exactly how many references they should have in their bibliography, or how their title page should be set out, or how many words over the word ilmit they can go, or what referencing system they must use.
What they're doing is using the unimportant stuff to try to help them feel in control of the actual thing we're assessing. They are trying to project their anxieties about the work onto me, and the practical details of the assessment task, rather than focus on Doing The Work.
It's the same here: some parents trying obsessively to determine the exact accurate magic formula for deciding which university, and which course will bring instant satisfaction, success in the degree, and salary/job afterwards.
There is no formula.
Choosing the right degree course at the right university for each individual student will have individual parameters and criteria.
UniStats and HESA data are all a year (or more) behind. And the NSS is really unreliable. We find that with a significant minority of students, one bad mark or one "bad" experience in the final year, can be enough for them to behave quite unprofessionally & childishly on NSS and other similar surveys. Academic staff (particularly women) regularly get personal & sometimes even abusive comments, or comments on what we wear, or our accents or similarly unprofessional and unthinking responses.
And the rule of thumb about low NSS scores sometimes indicating a level of challenge that current undergrads are increasingly unused to is pretty accurate.
There's no substitute for doing the research via university websites - you need to get beyond the UCAS-facing pages, and into the webpages which departments use in their daily work. This is harder at post-92 universities, but look for pages such as "About Us" or "Departments and Schools" etc etc.
Then do the leg work: visit places. Let your DC visit on their own. Start to get a feel for the kind of living/studying experience that each person is suited to. We're all different (thank goodness).
But there's no formula or set of statistics even deliverable that will give you a magic fortune teller's ball.