Well both are reliable, Overall quality & complains yes for Suzuki GS I have seen users complaining for quality issues. Situation at once was really poor But engine wise its reliable. I had bought cg125s, Its just good but not value for money still with same old ohv technology engine and vibrations are still present not good for long rides or tours. But for city its good.
Parts availability obviously cg parts will be everywhere available and gs parts also available but at authorize dealers. And parts that you are mentioning don't wear out or tear too quick. So parts would not be issue for both bikes. You will be able to manage.
