I went with the primio viaggio. I think its sturdier so felt it was safer, however as a result it its bulkier to lug about.
In all honesty, i we just wanted a carseat, rather than an infant carrier that attched to a pushchair, then I would (and wish we had) just gone straight to a group 0+1 though.
The primo is very limited with a weird recline position, so I would definitely get one where the recline angles can be different.