Are you going to ERF? Type of car? Are you looking for something that would get you to (possibly) the end of car seat days?
We have a Scenera, a Nautilus and a Triumph. Love the Triumph, even though it is a large seat. The Nautilus is fine, no complaints. DS is very comfortable in it. The Scenera has been great for travel and in the 3rd car.
MIL has a Sureride, my only complaint is that the shoulder straps are closer together and dig into DS' neck.
Our main vehicle is a jeep grand cherokee, so seat size might not be too much of an issue, but it might be in dh's truck. I'll definitely check on that.
I would look for the tallest seat that fits your car and your budget. That will give you the most longevity both RFing or FFing (so you can go straight to a booster around 5-7 instead of having to buy a taller FFing harness seat when your kid outgrows a cheaper convertible).
That site has a comparison of how much space they take up front-to-back (in relation to each other) and also a list of how tall the shell is/the height limit of the seat.
Graco 4Ever (maybe the Milestone, which is the Target version - I haven't tried that one, but it is fairly similar) - my current favorite and one of the tallest yet most compact seats because of its headrest design and the number of recline positions (there are fewer on the Milestone, but it will still probably be a good option) Nextfit Headwise (Size4Me/MySize - not the MyRide)
These three are probably not at Target (in-store), but they are decent options Radian Complete Air Pria
Unless you have a really gigantic vehicle with a lot of room between the front/rear seats, I would look for tall seat that don't take up a ton of room front-to-back. It is much easier to keep a kid RFing if the front-seat passengers are comfortable (and if you buy a seat that will only RF in the middle because of its size, you may be pushed into FFing sooner than you would like if you have another child).
We used this info to pick a seat and bought the Chicco Nextfit at BabiesRUs yesterday. It hardly takes up any room front to back, rear facing (less than her infant seat!), compared to the Britax Marathon, which was our other top choice. DH liked the looks and the installation ease of the NextFit right off the bat. I was a big fan of the ERF option, and the good safety ratings. It was a no-brainer when we got to the store and compared it with the other seats.
ETA: Thanks @fivedogs because I think you've posted this info before and I found it invaluable when we went looking for a seat.