I currently have 2 ‘audax bikes’ if thats actually what you mean, guards, dynamo lights etc. One is fixed and steel, the other aluminium/carbon with gears. I rode 300 mile over 3 days last summer on the alu one, it was nice and comfy compared to my previous alu ‘racer’. The fixed only gets used for rides 40-50 mile, its very comfy, more so than the alu one, but has at least 4lb on it and dosnt even have gears!
You can get lighter steel, stiffer steel, comfier alu. Really tho you wont know until you try 2 specific bikes which one is ‘better’ as weight/comfort are subjective to a point, expecially as you cant say anything about the Alu one your looking at.