It depends on the reputation, condition, parts availability, and price of what I conveniently come across?
I have a few plastic case saws that some on the forums wouldn't speak highly of. They have worked fine for me. Some lesser or older ones I have given to my kids and they have not had any major problems. I have to still work on them on occasion but it has always been filters, lines, carb diaphragms, and with one kid - to sharpen the chains. I have or have had most of the more popular brands.
Some I didn't like was a 1838 Chinese Mac. Had a 1432 Mexican Mac and it was great. I had a couple plastic Homelite 45cc saws that run half speed compared to plastic Stihls but the kid likes them. I had a 150XL vibrating Homelite for 20 yrs. Never worked on it but got tired of the vibration. Had a Mini Mac 10 that was more aggravating than useful.