You have to buy what you like and what you think will fit your lifestyle better. Personally, I find the IWC Portugeser Chronograph to be all shine and little substance. While its look is distinctive (either you like it or you dont, I fall into the I don't catagory), but the movement is a rather basic Valjoux. Yes they say they modify it but unless you are buying one of their split second chronos, IMHO there are not enough modifications to differentiate its movement from that found in several less expensive watches. I'd rather have the Submariner for a first watch. Its more rugged, if you don't have a dress watch it doesn't look bad with a suit (although a true dress watch would be best), and the movemnt is made by Rolex. I'm not one who has to have an inhouse movement in a good watch, but if its not an inhouse movement I want it to be a higher quality movement like F. Piguet, Piaget, JLC, or Lemania to name a few. If you want something high quality that is a little less conspicuous I'd go with something from JLC.
I on the other hand like the look of the IWC Portuguese, but I'm gonna have to defer to Dino on the $$$$ point. They are overpriced for what they offer. No doubt about it. I'd scope out Maurice de Mauriac or a Bell & Ross before I shell out big bucks for an IWC.
Personally I think Blancpain can be a little overpriced too.
Can't go wrong with a submariner or a JLC MC for your first watch.