blau
3496
I vote with my wrist!
Breguet:
Or, wait, maybe Zenith...
I don't know which of these I'd keep if I were only keeping one. PROBABLY the Zenith since it's more unique in my collection.
But one thing to note about your long list is that two of them are very summery (Zenith but *especially* Heuer) with bright, sharp contrast colors on the dial, and two are very autumnal (Breguet but *especially* Breitling) with dark and warm tones. If you're really thinking in *wearing* terms and not in *pure watch collecting* terms you might want to consider the circumstances you'll want to be wearing this one in, and take that into account.