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.