Iconic to WHO exactly? Current Military, or WWII vets ? Fans of military history? Old movie buffs? Gangster/thug types? People under age 21 ?
Serious,hardcore pistoleros ?
All of these groups will have widely varying views. Under 21 might say Glock, serious pistoleros willl probably say 1911, old war movie fans might stick with the Luger, and so on.
All that being said, I don't think any of those mentioned here outshine the venerable 1911. It was used in every US war since WWI, has been in innumerable movies and TV shows, has been associated with both fictional and real gangsters from the early 20th century, and is probably the most replicated/copied weapons design in history.
Numerous companies have built their reputation on it, and have numerous versions avaialble. You can find versions of the 1911 that function properly, from as low $400-ish, up to several thousand. You'll never get to the end of the list of after-market parts available for it.
After over a century of newer designs surfacing, it is still a big favorite among the military, and among competetive shooters. IMO, no other semi-auto even comes close to being as "iconic".