John Deere is autoquad , Valtra is powershift , which if believe is the same as MF dyna 6G series Valtra is definitely dyna 6 in hitec spec but I think the op was talking Vario? Not sure what the JD was, probably powerquad?
You need to compare like for like as others have said. The Valtra would be more compact and nimble with a Quicke loader which is much better than JDs offering. There are Valtras around with massive hours on them so no worries there. Horses for courses and dealer back up will be important.