You can't compare like this, you should narrow it down at least to some cities. Porto is better than Alicante, Madrid and Valencia are the best cities on the peninsula.
I know. I lived there. Still beats anything else on the peninsula and no part of Portugal comes even close to what Madrid offers.
Cons: If you move to a hot part of those countries then climate change over the next 20+ years will probably kill you before your age does, or at the very least the sweltering heat will make life miserable for a significant portion of the year.
It really depends what you like/want
Spend a month in each city and decide
Having said that, I have always been with the impression that everything I can have in Portugal, I can have in Spain, however, the reverse is not necessarily true. Admittedly, the Bacalao obsession has diminished recently a bit in Lisbon, but interestingly enough, the best seafood I've been having is in Madrid. Not Lisbon, Barcelona or Valencia. In general, the food scene in Madrid is one of the most exciting ones in Europe. I think the stereotype that Barcelona is the food capital of Spain is long gone.
The other thing I highly appreciate in Madrid is that it's so central and well connected with high-speed RENFE, that traveling to Catalonia, the Basque country or Andalusia is fast, very pleasant and picturesque. As a foreigner I also feel much more comfortable in Madrid, it's much more international (not only from the perspective of touristic crowds) than Lisbon which is still much more local, if that makes any sense.
People say it's cloudy and rainy, but come on...my new standard for cloudy is the Swiss plateau
Oh, absolutely, cannot agree more! What's not to like! Best steaks ("retired" dairy cow is the best possible response to the "aged" young beef in other countries), rugby and some of the most interesting pintxos. I took this photo on a trip to Santiago as I don't recall ever seeing rugby in public spaces elsewhere across Spain (although they will play in the world cup this autumn)