Here's my take after going through garco Snug fit 35 with the carrier that lifts out as a newborn and Graco Extend 2Fit in both rear and front facing configs... Diono Radian 3R, Graco Affix, Garco Turbobooster LX. I've spent nearly $1000 in car seats over the last 6 years and probably nearly as much on strollers.
All in one car seats suck. They make a lot compromises so the seat can grow with the child. Often you end up with the seat being overly large when the child is small. When the child gets larger, less features are needed and the seat can be slimmed down, but all those 2 and 3 year old features add to the packaging heft not needed at that stage of life. Also sinc all the straps and buckles must also work at age 2 and at 5 since the seat is designed to work through multiple ages, the straps and buckles can be disproportionately large when the child is young.
Given all that, I wish I would have went with more car seats at different stages of the child so the setup, packaging and use could be simpler. Most of this is mostly behind me now.
The insight is not that big so space is a premium. If I were to do it over again, I would look for simpler smaller packaged car seats and ones designed for a specific stage of life. However this is easier said than done. Mass market car seats are mostly do it all designs that lure parents in with tons of features, as the parent thinks this seat will last forever through multiple stages. Again the compromise is $$$ cost, complexity, large packaging, and a doesn't fit so well at different stages. Car seats costing $200 is normal and when you need 2 or 3 at a time. It gets pricey.
The only car seat I really liked was a Diono Radian 3R. It's slimmer and simple to use once it's setup and hade really nice materials and color scheme. However, you probably won't use that until your kid is about 3.
Another thing we do is resell our car seats when we no longer need them. I recently resold 2X Graco Extend2Fits for $80 each. They were $209 new when I bought them. They are $234 currently. I replaced them with $80 Graco Turbo booster LX and Graco Affix which are the slimmest booster seats I could find.
I didn't like the Extend2Fits large packaging, but when your busy going through life, sometimes you don't have the time and energy to find a perfect car seat.
