I voted for one and three. In 5E I generally start them at 1, but the longer I play 5E, the less benefit I'm seeing to this.
I used to think the 1-3 leveling in 5E might introduce people to the game well, but actually having played with new players, it seemed like it introduced more confusion as they suddenly got a lot of significant new stuff, than it solved. Whereas just starting at 3, you can explain everything once and people don't miss stuff or get confused. The only downside is people potentially taking a bit longer to select spells.
Also 5E is at it's most wonky and unbalanced from levels 1-3 (as has been kind of discussed in other threads), and that can actually set expectations for newer players that don't hold at higher levels, so I find that's not very helpful.
For older players I don't think there's any real benefit beyond tradition. If I made a new edition, I'd be very tempted to basically make what is level 3 now, level 1 (in pretty much all regards), and in the DMG offer an optional "level 0" experience, which was heartily disrecommended for new players and designed as an OSR/nostalgia-trip deal.
In 2E we just always started at L3 in all campaigns after Dark Sun. In 3E, we tried starting at level 1 like twice before deciding it was pretty pointless. 4E's level 1 was about as sturdy and functional as L3 in other editions, so we did start at L1 there.