Which Tiffany?

Welcome! I vote number two. A friend of mine has the heart return to Tiffany one and I was shocked at how cheap the chain looks IRL. IRL it looks like a chain from Claire's! So I'd stear clear of that one!!
 
Elsa Peretti round- it's the most simple and sophisticated and will be a timeless piece. The other ones are more trendy and may be out of style in 20 years.

BTW I love Elsa Peretti, I have some of the teardrop stuff and it's fantastic.