But seriously, folks: I have the Lionel Dreyfuss (both of them: the Century-style and the Empire State Express style). The sound beats the others. And I use TMCC mostly. But, MTH is great also; the sound is not as deep (may not matter). I have a 3rd Rail NYC J3 (non-Dreyfuss); fussy. Had to work on it here and there to get it to work. The sound is early Lionel (OK, but...). The Lionels were out of the box, lube, slap it on the track, and go. I recommend, from experience, in order (and not considering the operation system or a die-cast/brass preference):
Lionel MTH 3rd Rail
Weaver and Williams (NOT the real early Williams) have both offered nice brass Dreyfuss locos, but this was before TMCC, if that matters to you. Upgradable, for sure.
And go on eBay eventually and get you a little Postwar Lionel #221 2-6-4. For fun.
They are all fine models, but the questions you have to answer for yourself is....what do you hope to get out of the model? What operating system(s) are you using? How important is prototypical detail? And what about sound?
First, MTH: MTH has issued the premier Dreyfuss multiple times, with different Protosound installments. These models are basically bulletproof, and are nice renderings. If it's scale fidelity, a decent-running model, and decent sounds, this model is for you. Price wise, it can be found from $500 - $895.
Second, Lionel: Sounds are incredible on Lionel's newest model. (I'm assuming you don't want the brass Smithsonian model from the 90's). The model has driver lights , TMCC, a wrap-around striping on the tender (MTH does not). This model is hard to come by, but with a little patience, can be purchased anywhere from $750 - $1100.
Third, 3rd Rail: Most would agree that if it's prototypical accuracy regarding valve gear, cab, siderods, paint application, etc...then this model's for you. It will also come with a robust, although generic version of Railsounds and will be command controlled. Don't know the price point here.
In sum, you have to scrape up videos on YouTube, ToyTrainRevue, and the like, and decide after you do your homework what model you need to have to satisfy your desires. Truth is, if there was one model of this engine, and that's all there needed to be, there wouldn't be all the replication, because different buyers desire different things.
A lot also depends on if you desire 4-chuffs per revolution. Many, if not most of the Lionel models came with 2-chuffs per revolution. I have a friend who owns the Sunset/3rd Rail Dreyfuss model and it is truely spectacular!
If you are looking for scale engines there out there, but expensive. Just the engines new if you can find one will go for $750 to $1000, even more sometimes. The Mth version's are easier to find than the Lionel dreyfuss #6-28084. I have all three, both MTH, and just found the last Lionel new one in a box out there I think lol. Had been looking for it for years now. The Lionel is to me the nicer of all three. The first MTH premier #20-3045 is just to light in color but I like the wheels it has, shinny silver boxpok drivers. The Lionel 6-28084 made about the same year but has the scullen disc drivers, and nicer grey color. There is a good review of both engines, titled Two Dreyfuss Hudson’s by Joseph Stachler of toytrainrevue.com just Google it and I am sure the review will come up. The cars Lionel 6-15326 made for the engine are really hard to find as well, its a 15 inch six car set. They also made a sound diner car 6-15383 which I do have. If you find the Lionel set of cars they will be very expensive, have seen all seven cars go for $1200.
The MTH dreyfuss made in 06 20-3217 is the correct grey, its proto 2 like the 01 premier engine. The 06 engine has the scullen disc drivers like the Lionel TMCC of 02. The MTH cars for the 06 dreyfuss #20-65094 are a good match for the Lionel 6-28084. The color is almost a perfect match, even the strips match the Lionel engine very well. MTH also made a sleeper/diner set, a rpo car, and a full vista dome car. The MTH cars are 18" which match the scale engine size even better than the 15" Lionel cars.
As far as the sound quality the Lionel has the better sound, its rich and full not so with my MTH dryfuss engines. I feel the paint job on the Lionel is also better. Its really up to you what you like. There is a vid on u-tube comparing that Lionel sound to a 3rd rail scale dreyfuss. The sound of the 3rd rail is more like the MTH engines. There is also a vid of the light grey 01 MTH on u-tube. Thre dreyfuss is my favorite engine. I cannot wait till Lionel does it in Legacy.
There was a used MTH 01 Dreyfuss set on the bay, it was buy it now for $1295, engine and 6 car set. I know there is a brass very RARE 6-18027 SMITHSONIAN BRASS DREYFUSS in the display case at Mercer Junction in Mercer PA. Dave does not have a price on it but they go for big dollars. I never wanted that engine because as you know brass is very delicate, and scratches very easily. Good luck finding one you like, there great to see run.