[tony20009]

Both are great watches. I honest don't know which one I'd pick between the two, but right now, I'm leaning toward the GO, and that mostly because I assume it's got a smaller power reserve (PR) than 7 days. Seven days is a lot of winding to refill the PR. If you actually need the 7-day PR, I guess the IWC is the clear pic.

Construction wise, the only thing I can think of is that IIRC, the IWC uses an acrylic crystal and the GO uses a sapphire one. I happen to prefer sapphire crystals, but the crystal is hardly the "be all, end all" to a fine watch. Lots of good watches, Rolex being one, have used acrylic crystals until fairly recently.

I prefer a more "standard" sized watch, and in that regard, the IWC wins out, although at 44mm, the GO is still very wearable. Pick the one that looks and feels better on your wrist if all other factors are equal.

Styling matters are up to your own preference. I happen to like the blue markered IWC quite a lot, but I have a lot of watches too, so I don't mind choosing ones that are a bit "different;" I don't need one that will look good with everything or that have no color splash on their face.

That said, I think the GO is a bit better looking overall, particularly the one with the blue hands. On the styling front, the only reason I would not pick the GO between these two would be because I had a different GO in mind to buy later. GO stands out among high end watches in that their designers have an extremely good eye for aesthetics. Nobody implements asymmetrical balance better than GO and if I had my mind aimed toward a Panomatic Date, or even a Panomatic Counter (symmetrical), I'd hold off on the Senator Observer.

Since you've shared nothing about why you are making this particular watch purchase, it's impossible to suggest one with a mind toward which would be better for you. There's nothing about either watch that is so overwhelmingly better/worse than the other that absent your requirements I can suggest one over the other. Having no info about you or your expectations, I'd say buy the one that you can get at the lowest price or at the best discount. I can promise you that a "test drive" should make clear which you prefer and that's the one you should buy. Both are very nice.

All the best.

Edit:
I check the IWC website and the Portuguese does indeed have a sapphire crystal.