Have a 4255 - similar size but older. I really like mine and it's done a ton of work for me, probably more than it should've 6000 hrs on it. Mine is extremely simple - pre def, standard trans, mechanical engine. Parts easy to come by - any AGCO dealer. Reasonable price for most stuff.
I've had very little problem aside from a few things. Bolts for the frame that holds the drawbar on came loose/broke. I repaired and just keep an eye on ever since. Bolts between two sections of the trans are too small and work themselves loose. I've replaced loctite'd etc - recurring problem I believe there's bolts under the cab that I can't get to without lifting the cab that are loose and I haven't tightened yet. They usually come loose one or two times a year - strangely always right around freezing. Front driveshaft has a stupid system where a splined collar slips over 2 shafts locked by a Cotter pin. Pin breaks, collar slides back, no Fwa. Easy fix but must be done or makes a racket and wears the collar,/shafts. All my issues are probably caused by/made worse by asking too much of the tractor for years. Pulls a 16' haybine all summer, was main feeding tractor, hauled 700 bales a year on a trailer with 17 1400lb bales for miles and miles for a few years.
The two models you mentioned - one is the 3 cylinder one is a 4 and neither is a Perkins - I would look for someone who's put hours on those engines and see what they think. I've heard nothing about either.
I bought another AGCO tractor - different brand (Fendt) if that tells you anything.
