Collection advice - where to next?

[jason042779]

My collection is in a great place right now, I feel very lucky. But I do have a big birthday coming up and possibly a career milestone, so I'm thinking about the next acquisition, as I'm sure people in here can understand. Where should I go next?

The core of my collection is:
ExpII Polar 42mm
18038 DD, YG champagne dial
JLC Reverso duetto travel time, steel
Grand Seiko Snowflake
Seamaster Electric Blue wave dial
FC Worldtime
Several Seiko divers

I tend to prefer modern watches from established brands. I don't use chronographs and prefer divers/sports watches, dress watches, travel complications or calendar functions. My Rolexes and JLC are lifetime keepers, anything else could potentially go. Budget probably $10-15k max. Any suggestions? Doesn't have to be Rolex necessarily. Looking forward to what the experienced collectors in here might think!