I had all brass, then went all steel, then went to the steel-brass combo. Best of both worlds. The high E,A,B (and D) enjoy the warmer tone of Brass, with less spikey harshness in the high end and slightly more mids compared to the steel. And the low A,E benefit from the slightly lounder, punchy, tight low end growl of the steel.
-thats my experience anyway. I've never had aluminum on a tele.
I do have an aluminum bridge on my Gretsch and find the aluminum to be bouncier, glassier. Brighter and poppier compared to the chrome plated steel that it came with.
Picks have a lot of variation over tone as well, especially in attack. Fender Celluloid picks are bright and quick, Delrin picks are mushy and dull.