Looking to upgrade to under bed gas tank

[JrCarr]

Hello everyone, I am looking get a gas tank and just want to hear opinions on different tanks. I want to know the pros and cons to each tank and what everyone thinks or recommends. My truck is a 70 C10 and I am looking at three different tanks. The first is a Boyd Welding 20 gallon aluminum tank that runs about $500, the second tank is a CPP 20 gallon steel tank that runs about $400. The last tank is also a CPP, but a 17 gallon steel tank that runs about $250. All three are for a carb set up and include the sending units and hardware. I'm just curious to the which is better the aluminum or the steel? Is there a benefit to one of the other? My thought is if I can spend only $250 on the tank it will free up money for the next part. So I see it as I can either get one tank for $500 or a tank and something else for $500. Any advice or input will be appreciated.