Travel systems are great at first for 1st 6months or so until kid outgrows it. We had the graco travel seat which was super-convenient. You buckle kid into carrier at home and then really don't need to unbuckle...can just snap carrier into base easily. You can buy multiple bases for different cars. Same seat can buckle into graco stroller or most shopping carts.
However, kid will outgrow this quickly and the you will need bigger convertible seat (ie you will need BOTH).
infant seat till ~6 mos old
rear-facing seat until ~2 yrs old (old recd was based on weight + min 18 mos)
then forward facing seat until at least 4 yrs and 40lbs
then booster (this is as far as I've got)
Basically, you will buy a bazillion car seats no matter what. If you choose carefully you can get car seat that will take you from ~6mos to ~3yrs or so though. Then you can buy a combo seat that is forward facing and converts to booser like Recaro ProRide?. For now, just buy the travel system and you will have a while to worry about the rest (I'm sure new seats and recommendations will come out and you will figure it all out as you go along).