patekkie
1552
Hi Andrea; Were it my choice, I'd definitely go for the 5907. It has a display back...
where the 3670 and 5920 do not. What's more, the 5907 has a lovely power-reserve display, visible through the sapphire back.
The movement on the 5907 is a HW version of the Piguet 1150, (auto version used in the 5920), where the movement in the Heritage is, I believe, a Lemania 1352.
Had you considered the new Ladies' 8067, with MOP dial? It has an ETA 2000 movement visible through the dipsplay back, and it's only 30mm. Unless you want a larger watch, this one looks to be a nice choice too.