Your favorite car seats?

Tiffany • Vegas Native ✨ | LEOW 💙 | Mom of 3 👧🏼👦🏼👧🏼| Home and Natural Birth Advocate 💕
So my husband is a RESEARCHER! I love it about him! I want to help look for the safest, easiest to use and more or less cost effective car seat/stroller combo for our first little one. What do you love about yours? Is there features that we will find super helpful?? Some we could rule out when looking?
Also, I have no idea about safety regulations and all that but we would love the Orbit system but the whole thing retails for $1100+. 😳 Hubs found some for sale on Craigslist but I'm not sure how I feel about "used" car seats. I think it's weird and potentially not safe. Thoughts? 
Here's a link to what we want! 
Thanks bunches in advance!!! ☺️
http://www.orbitbaby.com/products/g3-infant-car-seat-and-car-seat-base?gclid=CJC0m4GE2soCFVKEfgodUjcP6g&gclsrc=aw.ds