If by travel system and the examples you wrote you mean something full-featured = compatibility with a car seat but also a reversible seat and so on, the Mios, form my point of view, is one of the best choices in this category. It is more spacious than others, has a sturdier frame with suspension, and overall is very well made and nicd to push. Just my two cents there - the Veloce/Vivace are not, by far, as nice to push, and I cannot guarantee the right adapters are available in your country to pir those up with a reclinable car seat.
Apart from these, there's the Silver Cross Spirit that is 51.5cm wide, however it is, features-wise similar to Mios but definitely not superior (and also much less roomy). The ABC Design Limbo is another super narrow option (48.5 cm) however it is also much less spacious and a bit basic. Lastly, there's Recaro Lexa Elite but that is much more meant to travel and should be taken for such.