Considering your collection.....

I have to say 5980R but that's not necessarily my favorite choice, I LOVE the 5726 1/a. It's one of the best in the AC line. All around the 5712 1/a is the most classic and elegant. I a.so think it will stand the test of time. The blue on the dialmis one of the best dials I have come across. Issue is in your collection the 5712 approximates your RO Dual Time and the 5146 competes with the 5726. Funny enough I have owned a version of all the watches in question. I gave up my 5146 for a 5726 (with some change left over ;-)) and I gave up my RO Dual Time for a 5712. I had a 5980 1/a but found it uncomfortable and traded it for a RO PC (that was a mistake). There are no bad choices here...only choices. All awesome pieces.