Look at Remington, Beretta and Browning gas guns...and I'd stay with a 12ga...there is a lot more variety in shells out there for the 12ga ( like 1 oz and even 3/4 oz loads in a 12 ga )...
Rem 1100's and 11-87's ...are older technology ...but they're solid guns ( if they are newer versions with changeable screw in chokes).
Beretta has made a number of models over the last 20 yrs....390's / new model 391's ...are still all over / most used...but still solid guns...
Browning used to make a Gold series semi-auto in 12ga..( they've dropped it now, except in a 10ga ) but there are still a lot of Gold models around - even new in box, and affordable....and the newer series is Browning Silver..both very nice guns for a new shooter...
Honestly, I would stay away from most anything else..Franchi, Yildiz, Weatherby, Mossberg, etc....they don't hold up to long term target usage of 5,000 shells a year or more...