Do some research: Go to the library and get Consumer Reports magazine and find its latest ratings of car seats. Also, go to www.cpsc.gov (Consumer Product Safety Commission) and search to see car seat recalls in recent years -- you will probably find some companies that have repeated recalls and I'd always avoid those. You can also go to www.nhtsa.gov (National Highway Transportation Safety Administration) to see what they recommend; as of today the NHTSA web site has several items on car seats and car seat installation etc. on its front page.
That said...I always used Britax seats and believe they are worth the cost. You will be using these items every single day of every week possibly for years, so on a day to day basis, the cost isn't really that great. A friend's toddler son was in an accident where their van did 360-degree donuts along a DC street but he didn't even notice and didn't budge one inch. He was in a Britax.
One other thing -- you said boosters but your sons sound young for basic "backless boosters" that just raise them off the seats and use the regular seat belts. Do you mean convertible car seats or boosters with backs? An 11-month-old is not ready for a booster, even one with a back, but needs a larger car seat for quite a while to come.
Oh, and keep your boys in a five-point harness as long as you can get seats that fit them and have the harnesses. I wish my daughter could be in one but she's eight and way too tall for even the biggest big-kid seats other than a basic booster!