If you are okay with the smaller boot, then Swift is indeed a better option compared 1.2L City.
There are no inherent transmission or suspension problems in Swift so far, or what I have heard of. Although, there have been 2-3 reported cases on PW / FB where people faced some issues, but that can happen in almost any car tbh.
I will let others share their opinions as well, but to me personally, Swift GLX seems a better option compared to 1.2L City.