I would not agree with how long they last, I have recently seen quite a few steel tanks fail hydro, some at their first hydro (5years old). I have 1 AL that has 4-5 hyrdro's on it now. That's not to say steels is better or worse, but longevity should not really be a concern. If you find it worth buying your own tanks, then the useful life will mean that hydro/VIP cost, no different than the your regs are the real cost of ownership, not the up front cost. Most of my tanks have 200 dives on them each, meaning cost per dive on the purchase is nothing.
I believe there is a lot more to think about for tanks than just material. You need to look at how you want to use it. I have both tanks around, some I use some for beach dives in warm water, some with drysuits and cold water, some with nitrox and longer bottom times.
Al80's are a great tank is you plan to travel for a good portion of your diving, this allows you to become familiar with the buoyancy and trim of the tank that you will be renting with you get wherever you go. unless you are a smaller framed person (think <5'5" and <120#) there is no reason to even look at other AL's, if you are the small frame, then a AL63 is a great tank. its shorter than the AL80 and people this size generally have low enough air consumption that 63 cuft is plenty for most recreational dives. its shorter size will fit your torso better and you should have better trim and comfort (but again, the AL63 is not a commonly found rental tank)
Steel- if you dive nitrox, use a drysuit, or otherwise need a little more air, the HP100 or LP95 are awesome tanks. They are about the same weight and size as the AL80 but hold more air. When you travel, you will find that steel tanks are hard to find on rental. Steel, as already mentioned has some benefits in being nearly neutral or negatively bouyant at the end of the dive.
Now, if you are a tech diver, eh... this is a beginner forum, not aimed at you.
I believe there is a lot more to think about for tanks than just material. You need to look at how you want to use it. I have both tanks around, some I use some for beach dives in warm water, some with drysuits and cold water, some with nitrox and longer bottom times.
Al80's are a great tank is you plan to travel for a good portion of your diving, this allows you to become familiar with the buoyancy and trim of the tank that you will be renting with you get wherever you go. unless you are a smaller framed person (think <5'5" and <120#) there is no reason to even look at other AL's, if you are the small frame, then a AL63 is a great tank. its shorter than the AL80 and people this size generally have low enough air consumption that 63 cuft is plenty for most recreational dives. its shorter size will fit your torso better and you should have better trim and comfort (but again, the AL63 is not a commonly found rental tank)
Steel- if you dive nitrox, use a drysuit, or otherwise need a little more air, the HP100 or LP95 are awesome tanks. They are about the same weight and size as the AL80 but hold more air. When you travel, you will find that steel tanks are hard to find on rental. Steel, as already mentioned has some benefits in being nearly neutral or negatively bouyant at the end of the dive.
Now, if you are a tech diver, eh... this is a beginner forum, not aimed at you.