I've only run one marathon, but I ran it in the Kinvara 2, which I really liked. At that time, I was using the A4/5 for shorter races (up to half). I LOVED the Kinvara 1 and 2, but the 3 and 4 haven't worked as well, so I've been trying other shoes.
I've found that the Nike LunaRacer3 and the Adidas Adios Boost feel VERY similar. Also in that category, but even less cushioned is the Mizuno Hitogami, which I've really fallen in love with. BTW, I believe the Ronin has been replaced by the Hitogami.
All three have relatively little cushion, and a heel-toe drop of 9-10mm
If you're looking for something closer to the Kinvara (i.e. a it more cushioning, and a lower heeldrop) I recommend trying the Brooks Pure line. The Pureflows and Pureconnects are very similar, but the Pureflows have a bit more cushioning, while the Pureconnects are a bit firmer, with a pronounced arch in the shoe.