Haven't Touched O-gauge in awhile but my recent grab engine wise was the '02 Era MTH Premier PRR M1b.
When I opened her up she had zero signs of any wear of running on a layout and the "white battery of death" (Don't worry I replaced that dreaded thing with a BCR)
Lying low on scale locos until something catches my eye or when Lionel releases a new run of the M1a. (I am itching for a legacy 6755 with accurate train phone antennas)