My dad and I used to argue about what to get, he wanted a GLS CVT Lancer while I on the other hand suggested to get the Vios thinking it was more economical to use and maintain over that of a Lancer. In the end, he got what he wanted. We opted out for the Lancer because it looks cooler than the Vios, parts are also abundant and not everybody gets to drive one. Not to mention, aside from all the extras the SA offered us, we also got a 55t price cut (745t slashed down to 690t).
The top of the line unit of the Vios (S variant) is a lot more expensive than the GLS, so we decided, heck, Lancer it is. :D Apparently, the only issue we can think of at this moment is the FC which falls in the 7.5~9city, 11~12Hway and +-9kpl mix.
If you're bothered by the FC, and want to save up on gas get a vios instead. For everything else, get the GLX or better yet a GLS. :D