Toyota Matrix insurance can be very cost effective considering the size of the vehicle and considering Toyota's reputation for quality and dependability. Toyota has been making the Matrix for a few years now and it is considered to be very safe which in turn makes it highly insurable.
The 2.4 liter has a little more oomph to it, but you're probably not buying the Matrix as a muscle car. Thus, the 1.8 liter option seems to be the better of the two options, unless you want the more stylish S and XRS versions of the car.
Toyota Matrix XR Detail review