Avoid the 3-in-1 type seats like hte alpha Omega, Eddie Bauer, Safety 1st 3-in-1, etc. They make ok rear facing seats, and only ok for forward facing because the top harness notch on the back cannot be used in harness mode, only in booster mode, therefore the seat is outgrown in height long before weight, and when kids are too small for the booster. Plus the booster portion of ALL of htose seats have failed every single crash test miserably, so they should never be used in booster mode.
For the money that you owuld spend on one of those seats, you could spend that or less and get a seat that will last in the harness longer, and will be a better purchase. Here are some seats that are great, last a long time in the harness, nad fits kids well.
Graco MyRide 65- Will rear face to 40lbs, forward face to 65lbs. AWESOME side impact protection, most kids can rear face to age 3, then forward face to around age 6. Its $150, such an amazing seat for the price.
Evenflo Triumph ADVANCE will rear face to 35lbs, forward to 50lbs. Great easy to adjust seat, fits most kids rear facing to age 2/3, forward facing to age 5. $130
The Britax seats (Marathon and Boulevard) and Sunshine Kids radian (80, 65, XTSL) seats are amazing as well, they rear face to 35-45lbs (depending on model) and foward face to 65-80lbs (depending on model). They also can be tethered while rear facing, which is a HUGE bonus. It reduces rebound drastically.
These seats will let your child remain rear facing until at least age 2, and then forward facing in the harness longer until your child is physically and mentally ready for a belt positoning booster seat (usually around age 5/6 kids are ready physically and mentally). Purchasing a higher harness weight seat now will allow your child to remain more protected for longer, and then when your child outgrows the seat at an appropriate age, you can purchase a simple booster seat.
Please google EXTENDED REAR FACING, JOELS JOURNEY, EXTENDED HARNESSING, and consider visiting a CPST through www.safekids.org to ensure your seats are installed and being used properly.
A rear facing seat is outgrown when the child goes over the weight limit, or there is less than one inch of shell above the childs head. Feet touching the seat is NOT a problem. The AAP recommends children remain rear facing until they outgrow their rear facing convertible car seat, or at least until 2yrs and 30lbs.
A forward facing seat is outgrown when one of three things happens, the child goes over the weight limit, the ears become level with hte seat back, or the shoulders go over the top harness slot. When even one of these things happens, the seat is outgrown and must be replaced.