Hi everyone, can you guide me in the right direction?

We have a Roundabout and a Marathon and love them both, but DS has approached the limit for the Roundabout. He's 2.5 yrs old, weighs 40#, and is 39 inches tall.

We have an Odyssey and an Accord.

Would you recommend the Britax Boulevard over the Regent because of the additional side impact protection?

What might be the next best model for safety and comfort for DS?

Thanks tons, Kate