IWC, my friend, without any hesitation...
You'll get with the IWC a perpetual calendar, and a serious one!
I love the North / South Moonphase on this model.
Since you're looking for a Moonphase, I'd say that the choice of a perpetual calendar, even if more expensive, is a better choice, IMO.
If you're not stuck on a perpetual, you can also consider the Lange 1 Moonphase, a very elegant watch!
If money is not a poblem, the perpetua Lange is a nicer choice...
A rare beast, but very nice , elegant, and maybe underated is the GP WW TC Perpetual Calendar...I really love it!!!
Why not also a PP Nautilus 5712? Sporty, with an original look, this may be another interesting option!
Even if, for me, one of the sexiest PP Moonphase is the Celestial...
Some Vacheron Constantin, now...Exclusive, expensive but very exciting... My favourite...
Another nice bird:
An esoteric Perpetual, now, made by JLC:
In a more normal presentation:
Available also in Rose Gold, this may be an interesting and elegant option, as you have a PC, 8 Days Power Reserve and an original display of the moonphase... And the last, but not least, the De Bethune wqith its 3 dimensionnal moonphase, one of the most stunning! But sadly I don't have any pics of it... Hope this help. best. Nicolas