New Car seats - What to get?

I am about to have $720 in my bank account to replace the seats that we have in my car as I was rear-ended a few weeks ago.. So seeing what other people have as I haven't really researched booster seats for our main car since I bought these when each child was going into forward facing seats.

We are replacing 2 standard Maxi Riders (1 for each child). I have no issues with going with the Maxi Riders again (or even the AHR as I have found them on sale for $10 each more than what I was quoted for the standard ones). I want both the same so I am going giving one child something 'safer' than the other. DS is still in a 5 point harness, and DD can be in either a H harness, or normal lap/sash belt.

We have the Maxi Rider AHRs - DD1's is in DH's car and DD2's is in my car. DD1 has a safe n sound Hi line in my car with a sash belt. DD2 has to stay in the Maxi Rider for quite a while yet because she will still be too small to go over to a sash belt when she is legally allowed to do so at 4 years. Going to be a pain because with #3 coming its going to be pretty squished in the back with a meridian AHR, the maxi rider and the hi line (which has the same safety rating as the maxi rider but is considerably narrower). When DD2 is tall/heavy enough she will go into a hi line too.

We also have 2 of the Maxi Rider AHR's, the girls love them and I love the fact you can use the H harness with them and they really do extend quite well based on height.
I will keep both the girls in there's as long as possible or until DD is able to go in an unrestrained booster and can sit in the back seat on longer trips etc, keep them further apart and allow other adults to join us, if that's the case though i would sell the AHR and buy a booster OR keep the AHR for DP's car. (so he can take either of the girls)

We have two maxiriders AHR in our car and they are fantastic just really wide. There is a webiste that has all carseats listed and rated for safety but i"m struggling to remember what it is. I'll do some googling.

We changed from a Maxi Rider to the Baby Love Ezy Combo after our accident. Better price and from memory rated better than the Maxirider.

Here is the 2011 rating guide:
http://www.mynrma.com.au/images/Abou...Guide-2011.pdf