I've been looking around and specs-wise, the Hella Supertones win.

Hella Supertones: 118db * 6'
Stebel Nautilus: 115db * 6'

As for the Fiamms, ang nakikita ko lang is some models are rated *130db but walang nakalagay na distance.

Sa Supertones, they have the additional advantage/disadvantage of being semi-directional.

Sa durability, case to case basis talaga. Masyadong varied yung mga experiences ng iba sa Fiamms, Hella and Stebel.

*GlennSter and odell
Anong model ng Hella yung nasira agad sa experience niyo? My old/stock horns were Hella's kase and they where mounted sa front grill. Recently lang nasira kahit na laging exposed sa elements.