best car seat for moving between cars?

[Stefka]

We would like to get a second car seat that can be used in my husband's van and my aunt's car. Which car seat is very easy to move between cars? DS is 16 months.

I have one from Britax - can't remember the model. I had to switch it between cars earlier this week (due to having a hire car for a couple of days) and it took 2 to 3 minutes to switch over, if that. Britax Explorer STS looks like it's fixing system is similar to the seat I have.