HP 3442 steel 100 (I have 3), even with an "underfill" it will give you more than an aluminum 80, and you can take 5 lbs off your weight belt.
My second favorite is the HP 3442 steel 80 (I have 3).
My instructor son uses Aluminum 80s (I have 3). He likes them because no matter where he goes in the world, he knows what he needs for his weight. There is also a good reason to use these for tech/deep diving, and for a extra slung stage/tank, and for hanging off the safety stop with a reg attached.
And I have a LP steel 72 - use it for my airhorn on my boat - blows all season - even with the little ones wanting to "honk the horn" (I am cautious not to allow them to be nuisances nor to use it inappropriately giving confusing signals. No lectures please.).
HP 3442s 119s, 120s, & 130s are just too heavy for me. I want releasable weight.
So, for me:
Ideal tank -
HP 3442 steel 100s
w/ a couple of Aluminum 80s