Ive used 3 of the 4 shoes youre talking about, adios 3, boston 6 and zante 2 AND 3.
I thought the Zante 2 was ok, tight around the forefoot but responsive, same with the zante 3 just felt looser, maybe even a bit bigger. the ride was harder then I liked but it was still a decent shoe.
now the Boston 6 is my bread and butter. i use that shoe for long runs, easy runs and tempo work. its a great shoe and the boost is phenomenal.
The adios 3 is similar, bit tighter, snappier and still has that soft(ish) responsive boost.
You wont be disappointed in the boston 6s or any boost shoe really