This is my first post, so treat me gently!!
I have been shooting for 15 years, with virtually no experience of semis. My youngster has just started showing an interest, so on the recommendation of a very experienced semi shooter, I bought him an escort 20g semi. For the money, it is an excellent gun. We have had zero problems in terms of it functioning, and it is solidly built - although obviously not a Purdy. Sorry can't help on 12g, or the other makes you mention, but you will do a lot worse than choose an escort from my experiences.
Hope you find the gun you want