Running qualities, there's not comparison.
Bachmann seems very hit or miss, even int he Spectrum. Case in point: E33 Electric. Running qualities, ok. It's REALLY tight, it will run at far less power than it needs to start, and the headlights are worthless blue LEDs that don't even light up the entire number board. But the detailling is INCREDIBLE. Spectrum GP30 - have two of these, same road, different numbers, and BOTH have the exact same problem with a huge horrible paint flaw on the side of the cab. One has chipped completely off, the other is just waiting an errant touch. But they both run better than the E33.
Stewart F's aren't superdetailed out of the box - just add the $7 Detail Associates detailing kit for all the hand rails and lift rings and grabs all in once nice package.
And Stewart customer service is GREAT. I hope it remains that way under Bower. My F7 set came out of the box with a broken ladder on the B unit. I called up Stewart, even explained I got it on eBay, they shipped me out a replacement decorated B unit shell for free. Now I cannibalized a ladder from the scrap box and found an Athearn powered mechanism which actually fits so I will have a second powered B with a little metal grinding work.
--Randy