A white-dialed Explorer II is an excellent watch, but it's not a particularly dressy watch. I personally wouldn't lump the models together. The bulkier 216570 is more casual in nature due its size and the design of its dial/hands. The 16550 and 16570 slip easily under a cuff and therefore don't draw much attention to themselves.
The current model would be a better all-arounder if they'd left it at its original size (just like the Explorer I). I'll reluctantly grant that the increased diameter improves legibility somewhat, but that's the only advantage of going bigger, and it compromises the unbeatable versatility of the previous iterations. The 40 mm ones are great for someone who just wants to get a single high-quality watch for any occasion and be done with it, as they're dressy enough for almost any situation but are as durable as it gets in a mechanical watch.
Among currently-produced models, the steel Daytona and the 36 mm steel OP/Datejust (the Air-King and Milgauss could work, too) remain at top of the heap for versatility.