As long as the Athearn is genesis and not blue box they are all comparable. All have minor detail problems and all are good runners. I would do a comparison with a picture of the prototype and see which one most closely looks like the one you want to model. You won’t go wrong with any of those in my opinion.
For an excellent runner for the money, Stewart are tops with me. You can find them on Ebay and if you are into Santa Fe (as I am), there is often a selection of F3, F7, F9, and FTs.
With some KD close couplers and American Limited diaghprams, they look pretty good!
I bought myself an ABBA set of SP black-widow F7s, as released by Proto 2000 recently. The detail is great, and they look and sound fantastic. I recommend them very highly.
It is hard to beat the detail of the Athearn Genesis (with their Highliner shells) and the new Proto-2000. They also run OK. The sound and DCC electronics in the Genesis I would not recommend to anyone.
The only F-unit that Atlas makes is the FP7. It runs fine. Lacks the fine detail of their more recent tooling.
Athearn BB will run forever and pull a ton if you can handle the gapping windows and rough molded in “details”.
The BLI & PCM are OK runners and OK sound. My PCM set has the wrong horn programmed into the sound unit. Their service department response is to send it back (not likely).
The Proto-1000s run great and are probably the best “value”. Not great details.
Stewart in my opinion are the best runners of the bunch (even more so if you can find some of the old original runs). Once again not great in the detail department, but they were designed so the modeler could add details for themselves.
I do not own any Intermountain. The ones I’ve seen were club members who brought them down to the layout. These were the first ones they did not the latest ones. They seemed to run really smooth, but the plastic in the nose was so thin that I could see the “headlamp” through the body shell. Easily fixed by painting the inside of the shell black. The ones I saw did not have sound.
Bottom line is depending on what your priorites are you won’t be disapointed with any of them unless you care about the DCC/sound and go with an Athearn Genesis with sound.
Personally I’ve been beefing up my fleet with Stewarts and Proto-1000s because these are for real use on the trains and not
I have three F units - a Proto 2000, BLI, and PCM. Proto and BLI have the same (Quantum) sound systems and PCM has LokSound. Both are very good but have different F key functions which can get a little confusing. If I had to rate them 1-2-3 it would probably be Proto, BLI, and PCM (BLI and PCM are of course the same company)
I don’t go for powered boxcars much these days, but I do have an old turbo-engined Life-Like F which I use to tow a John Allen track cleaning slider car…not Proto anything; this is the one with the sidewinder powertruck. ducks
The scary thing is that it actually has somewhat of a low range on my transistorized Ampack, especially on pulse power. Of course it also goes up to 140 mph. I need to fangle in some RF suppression so it stops interfering with Law & Order when I leave it to run unattended.