Pretty much any watch other than the standard rollies or perhaps breitlings would probably make me strike up a conversation. Seeing someone with a mechanical of any kind these days is pretty rare round my parts.
The last time I saw a memorable watch in the wild was when the president of one of our suppliers came by for a meeting and brought along some upper middle management type to help him out. I could hardly believe my eyes when I saw that the new guy was wearing an alain silberstein. I'd been told there were interesting pieces out there, but prior to this I thought I'd have a better chance of spotting a unicorn than seeing something other than a sub.