Big baby twins + not so big car= WTF kind of carseats are best!?
We dealt with this by going to a big box store that had various seats in stock. We ended up with two Radians fitting nicely in our car, with room for a person in the back seat as well.
We had also considered the Maxi Cosi Pria, but the person there thought the Radians were our best bet.
But I totally suggest going to a big store with seats in stock so you can verify. (you can then order there or online if you want variants they don't have)
If you want room to recline without hitting the front seat back, then the AlphaOmega 3--in1 with the removeable base removed worked for us - needed pool noodle to get reclined enough (inexpensive seat too). But this seat is outgrown in the height much sooner than a radian (probably by age 3 for your boys). If you want something that will fit in a small car and last until the boys are probably age 5 or so (longer if they are average height), the I would get the radian.