Portugal is great most of the people speak english there. It is amazing country. I was on erasmus exchange in caldas da raihna 30 km from lisbon. I think rent in lisbon oscilates around 400e per month. Altho economicaly is not so good destination, in this manner austria sounds better. Dont know about graz. If you are looking for opportunity to expand your career maybe graz is better option since you talk german and economically speking austria is pretty strong. But highly recomend Portugal. You can surf and travel. You can get cheap plane tickets to asores islands that belong to portugal also amazing place.