I like the San Siro and try to go at least once a year. I was up in the third tier for the Juventus game in November and the view was a lot better than I expected. Usually I go to the second tier red. The derby games with Inter are very enjoyable. The new tube extension makes it very easy to get to and from Central Station. Food and drink outside is not too bad and a reasonable price. Match ticket prices vary according to who is playing with the derby and Juve costing around 90 euros for a cheap seat.
Milan as a city though is not a favourite. It's not too bad between May and September but most of the football tends to be played between September and May when, every time I've been, the weather is pants. Smoggy, foggy and drizzle or torrential rain.
I'd be happier if they knocked down Milan and left the San Siro alone.