As far as reliability, all of the platforms listed are known for reliability (some will question the AR, search the forum and draw your own conclusions)
Compact lightweight, I would say that rules the SKS out, and possibly the AK, the AR and the Mini I think would win in this category.
I own one of each with the exception of the AR, I own 2. I love all of them, but my go-to gun is the AR. I like the ergos, the accuracy and reliability.
No matter which you buy , you will have a good gun, I think to narrow it down completely, you would need to list ALL of your deciding factors (accuracy, affordability, expandability, durability, parts availability, thats alot of "ity"'s)