tank size

I'm currently looking into a Redundant Air Supply for recreational diving, and the only thing I'm unsure about is what size of tank to get. I've researched this enough to know to stick to 19cu or above. For Context: Most of my ~35 dives are solo, and around 30-60ft. I'm comfortable at 100ft...

If you could start your tank collection over again knowing what you know now, what would you include and why? I noticed that the last tank selection poll was from 7 years ago and I would like to see if opinions have changed since then. Also, not just see what people's favorite tanks are but...

my son has decided to take the plunge and I am extremely excited he will be joining an OW class in July. He is roughly 100 lbs so not the biggest of kids for his age as he is 14. I do not want him to get stuck with an AL80 for the class and because I plan on taking him diving with me whenever...