i would never put a young child in the middle with a car seat, side every time iso fix or no iso fix.. imo of course

 

I'm responding for anyone else who may be looking at this and wondering.

Middle is best if you can get a good install as you can't predict where you will be hit so it keeps them furthest from potential impacts.

As far as installing using isofix/LATCH or belt, whichever gives you the tightest install is the best choice. Also, isofix/LATCH has a weight limit that includes the weight of the seat as well as the weight of the child whereas there is no weight limit with a seatbelt install.

 

Yes middle is best if possible. Second best is the side that allows for curbside entrance and exit. That is typically the rear passenger side.