I’ve got 5 ABBA sets of Stewart F units - with all units powered, and each of those ABBA consists can pull whatever I can throw at them. Of course some will say “that’s 4 locos”, and obviously they are correct. Narrowing that down, I have a couple of Atlas RS 1 & 4/5 units that have yet to spin or stall. For what its worth, the Stewarts (Fs with Kato, FTs with Stewart drive) and the Atlas are my most run locos, and therefore must be favorites.
On the steam side, my Paragon BLIs pull great, and would pull more if I changed to the traction tires. I prefer not to, but we will see.
While I like long trains, having more than 10 or so passenger or 25 or so freight cars in a train on my 11x15 foot HO layout is overkill, so pulling power above those limits is unnecessary. But ain’t it great!
Proto SD60’s will out pull anything you can throw at them, they are the king of all stump pullers. A close second would be Proto SD45’s. For low end power Proto got it right in these two loco’s, nothing can touch them.
If your talking about one of the old 8 wheel drive Bschmanns from the 1970’s, they were very heavy, I still have some of those. They out weighed the older Atherns easy.
Get yourself an Hobbytown drive and an early Cary lead/antimony shell (one from before Don Stromberg sold the line to Bowser) and you are there.
The newer stuff with mega electronics can’t pull to much or they will become their smoke units. See a thread titled some like “how much should a good locomotive pull” towards the front of thsi forum.