Looking at an eliminator for a friend . Are the fuel tanks fiberglass or aluminum. Owners not sure

Mine are aluminum.

sorry for the dumb question but wich is better?
alu? stainless ?

alu trailer seems to do well in salt water... is stainless better? or mandatory ?

Stainless is better, however I don't believe I ever saw a stainless trailer. Stainless rotors are a must for saltwater.

Both my 25' Daytona and 28' Daytona have had twin aluminum tanks.