I only use Stainless Steel. I try to avoid poisoning my beer and my body with the aluminum contaminants
In the print edition of How to Brew, Palmer (who happens to be a metallurgical engineer) discusses that chemical analysis of worts boiled in seasoned stainless and aluminum pots showed no difference in detectable aluminum content, pre or post fermentation.
Per the Alzheimer's assn:
ALZ Alum PDF
During the 1960s and 1970s, aluminum emerged as a possible suspect
in causing Alzheimer’s disease. This suspicion led to concerns about
everyday exposure to aluminum through sources such as cooking pots,
foil, beverage cans, antacids and antiperspirants. Since then, studies have
failed to confirm any role for aluminum in causing Alzheimer’s. Almost all
scientists today focus on other areas of research, and few experts believe
that everyday sources of aluminum pose any threat.