A few thoughts....
I don't know how close you are to a gun store that would sell some of these rifles.
I strongly believe you really need to handle them first and get familiar with each one's controls and balance.
I have not owned a Ruger Mini - so I cannot confirm any pros/cons except that parts are more readily available than a rifle made overseas - not that parts are going to break often though.
I have owned an HK SL-8, CSA VZ-58 (I still own it) & a Tavor.
They all handle so differently but yet can be made to hold AR pistol mags - so that is a plus over the Mini.
The HK has a funny thumbhole stock and heavy barrel (and you notice it but it is the most accurate) plus ambi controls (are you a lefty?)
The Tavor is again an awkward beast to use until you get trained on it and it has a military pedigree oh, the trigger - could be an issue?
I find it handles comfortably after awhile and definitely better than the HK but it takes third place in terms of accuracy in my experience.
My favorite is the Czech Small Arms VZ-58 due to it's weight, price and handling, actually it is quite accurate if you are willing to mount a pic rail for a scope/red dot.
It has a chrome-lined barrel too - easy to clean if shooting corrosive.
The original CSA rifles brought into the country had some issues but in the last few years they have been solid.
A parts kit can be obtained without too much difficulty and that is all you need except if you want an AR magwell too.
Why not have 10 rounds ready to use but the plastic magazine well adapter could be made better?
It is somewhat of a bad time to be buying a rifle now that the Boxing Day/Week sales have passed but some still seem to be lingering on so perhaps you might find what you are looking for - if new at a decent price.
Buying used - well who knows what has been modified etc. but it might be a good price and worth the potential trouble.
Hope this helps.
