For me:
Shared driveway. Mostly it’s fine now, but that’s only because I’ve had to kick off multiple times at next door using my side or having their friends park entirely across my drive.
Not having a downstairs toilet.
Not having a separate dinning room (kitchen and diner are open plan and would be too small to divide). I’d still love an open plan with a table, but I’d like a dinning room for more formal occasions.
Potentially because it’s a semi detached, too much noise from next door.