Each material has its drawbacks and advantages.
Personally my favorite is steel. Why?
Steel is strong, steel can be cut with an oxy acetylene torch and it can be welded with a stick welder on a beach in some 3rd word despot somewhere.
When it comes time to paint the bottom, you can use dustless blasting on steel, which is blasting media sprayed through a pressure washer specially designed for blasting.
With dustless blasting you could strip a 50' boat completely bare in half a day above and below the water
line. You can't do that with a FRP boat.
Now when it comes to FRP, there are some advantages there too, the first of which being you won't have rust issues, and FRP is very strong to a point.
When FRP breaks it delaminates, meaning the layers of glass separate from each other. This can be a royal pain to repair, if not impossible.
FRP gives you great strength verses weight however, by weight it is stronger than steel, but in order to match the strength of steel you have to go much thicker.
I have mixed feelings about aluminum. On one hand it is strong and it is light, but aluminum is a material that likes to stress fracture. IF you have an aluminum joint that always takes a beating, eventually it is just going to crack in two.
Also on Aluminum plate that makes up the hull when it takes a beating and flexes it is also prone to cracking. And when it cracks it an be a real pain to fix.
If I found an aluminum boat I really loved would I not buy it? certainly not, but id be aware that these are issues I could have and plan accordingly.
Being light weight aluminum lets you have much more payload in the same size boat. I think that is a huge advantage.
You can also use dustless blasting on Aluminum but you do have to be more careful because if you over do it, you will burn a hole right through the metal.
The one advantage steel really has is that it can be fairly easily welded while still in the water if you know what you are doing.
Does that need to happen often? no.
Is it likely you will ever have to do it? no.
But it is nice to have the option say if you are 1500 miles from land in the middle of the Pacific with a hole in your boat, Being able to weld that hole shut would give me a lot of comfort even if I was just scabbing a plate over the top to get me back into port to do it right.
I hope like hell I never have to do that, but I will be prepared to do it if I do.