1. Any pantographed quill stem, especially Olmo, Colnago and the like. For non-pantographed stems the TIG welded ANSWER ATAC is beautiful to me, but so is the Cinelli Grammo. I always loved the beauty of stems that had hidden stem bolts and those that didn't use actual wedges but conical expanders. Not the most beautiful, but my favorite stems are Superbe Pro and MAVIC stems, though neither really "made" the stems, but they are rare as hen's teeth.

2. Quill stems are a.) heavier by definition b.) made changing bars laborious, but certainly could have evolved to removable faceplates. Then again, VHS tapes could have had a default "letterbox" aspect ratio c.) quill stems are flat out incompatible with carbon steerers, and dicey with thin wall titanium steerers, in fact aren't actually as safe as thread less if we are being honest about it

3. Like the look of lugged stems, even on a thread less setup on a aluminum or (ack!) carbon bike. Bonus points if the lugging is copper plated and allowed to patina. I like the ANSWER ATAC stems, Ringle stems, and even vintage Syncros stems. Modern Thomson stems are okay. I always like the crazy wacky carbon stems that came out of France in the 90s, that looked futuristic and forward looking. On a non-period epoxy bike they'd look silly, but they were a thing to behold.