FINALLY, something I have experience with for a First Post!
This is a loaded question, and the solution will vary based on the type of cars you are trying to lift.
My $0.02:
Aluminum 1.5 ton is good for a track/autox/portable jack that you are going to use to get a lowered, coupe or convertible, two seater just off its wheels. It will struggle and whine with anything heavier than 2,500lbs and compromises capability to be light weight.
The steel 2 ton seems good if you have an extremely low car and need to lift it quite high, but if you can sacrifice the extra bit of clearance the steel 2.5 ton is IMHO the best "Bang For Your Buck" jack that HF offers at $70. Low profile, has fantasric range, better capacity than the aluminum 1.5 ton, the padded handle is nice to have, and the darn thing is beefy without being exhausting to move around the garage.
However, if all you are lifting is Mini-Vans, Small Suvs, and 4 Doors then the steel 3 Ton is probably more suited to your needs and at $59 is the cheapest option. Reasoning: why get a low profile jack for an average ride height car, it just means you have to pump it that much further to get the car up.
If you need more info feel free to PM me.