I'd like to play devil's advocate here a bit if I may, though I largely agree with what some of the others have said. I thank Bazzar for asking for honest and constructive input...not every developer is so open.
I do think there is a certain amount of Fanboism in sims in general, though I don't necessarily agree with the sources put forward above.
Truly, I do believe that there is a certain bias towards companies like A2A or PMDG, but bias in terms of expectation based on past performance, not necessarily in terms of prejudice against others as such. Both A2A and PMDG have developed a well deserved reputation for having detailed, accurate, and beautiful products. This is not to say that Just Flight doesn't have a good reputation...more on that below.
Case in point. While I have never actually flown anything in real life that A2A produces (don't I wish), I can tell you that I used PMDG's FS2004 737 to prepare for my real world 737 training. Was it "full real"? No. Was it impressively real for the perhaps $100 I had put into it and FS2004 combined? Definitely. As such, I don't think that it's unfair if these products are met with a sense of expectation that they will be detailed and complete...they generally are. That's the entire point of building a reputation.
In some cases, this quality comes at a premium, and the fact that the PMDG 737 comes in at over $65 and the Just Flight DC-3 can be found for $30.65, should be lost on no one. But of course the fact that the A2A Stratocruiser (w/o Accusim), which is a really quite detailed and attractive product and retails for $36.99, should be lost on no one either. There is an unavoidably subjective cost to value ratio which "attractive but (comparatively) simple" aircraft are going to come out on the losing side of when compared to "attractive and (comparatively) detailed" aircraft when the price starts getting close. And it's here where reputation might nudge a buyer one way or another. I don't think that is necessarily unfair.
Before I go any further let me clarify that Just Flight does not have a bad reputation in any sense that I've ever been able to determine. It's just that, IMO, Just Flight seems known for making very good airplanes at approaching premium prices (my personal cutoff for that being the original cost of basic FSX itself) whereas A2A seems known for making planes with perhaps a notch more accuracy and quite a bit more systems fidelity for about the same price. Consider that the P-51 retails for about $30 as well.
And it's here that I think that the true bias comes into play. There is definitely a sense in sims, again IMO, that "harder is better", sometimes irrespective of whether it is more accurate or not. Not mentioning any product in particular here, but while it is nice to have a working Flight Engineer panel in the cockpit, there's a reason that pilots long to get out of "sitting sideways"...it sucks! Personally, if the flight engineer was traditionally responsible for managing fuel flow, I'm perfectly fine with him doing it in the sim. I don't need to fiddle with fifteen boost pumps to feel like I'm a pilot. Many others believe differently. Some excoriate others who note (sometimes rightly) that a sim seems too hard or unrealistic in some fashion. That's when the "it's supposed to be hard, it's hard in real life!" arguments come out; even if, in real life, it took three men and six arms to do the same job the sim pilot is expected to do by himself.
This is the bias that I think, sometimes unfairly, often plagues add on developers. Not that increased realism is bad. But that realism is often abnormally raised to be some sort of end in and of itself. Therefore I do agree that the accuracy increase to price increase ratio is definitely skewed somewhat. Still though, I don't think it's quite fair to slam those companies that put the effort into giving the community what it wants. It's just a quirk of the audience.
At the risk of blathering on more than I already have (I apologize, I can't seem to be terse when I write), I'll tell Bazzar (and the OP, God save his soul) why I personally chose the Just Flight DC-3 over the other offerings.
1. My Interwebz research suggested that the MAAMSIM DC-3 had a better flight model than the JF version. That said, I understood the JF model closely matched the stock DC-3 and I found the stock model to fly believably like I would expect a DC-3 to...which was good enough for me. I have had no complaints about the JF DC-3. She flies just fine.
2. The JF DC-3 is a newer model and by all accounts looks great on the outside. This isn't a failing necessarily of MAAMSIM. It's just an older product.
3. Much has been said about the JF VC. Personally, while I would like to see it more "used" looking, it's a good looking cockpit and, significantly, sharper I feel than the older MAAMSIM bird. It does have a ever so slightly "skewed" perspective to it that makes me feel like I am flying after taking too much cough medicine. But it still looks better to me that the muddy older cockpit of MAAMSIM which seems to have a more normal perspective.
4. One big negative of the JF product for me, and one which I gather is common across several of their products is the paint kit. I have several JF aircraft and I have often found that finding repaints online has been difficult. Based on the fact that I have seen several people now who have voiced complaints about the difficulty of using the provided paint kit (I'm not a painter myself), I can't help but feel that these two things are related. Perhaps this is to encourage simmers to purchase the expansion packs that JF provides which are generally well done, but add cost, which returns us to the cost/value discussion above. But I think it really helps to sell a product when modders produce thousands of repaints for a model...maybe it's the impression of getting something "for free" which is a strangely powerful incentive (things aren't sold with a free set of Ginsu steak knives for nothing). Sometimes though, it helps improve the product itself. The JF Wildcat has a few bizzare combinations of aircraft roundels that are decidedly ahistorical. Since my old squadron has a very personal connection to the Wildcat, I'd pay good money to have someone do it right.
In the end, JF's good looks and believable, if (reportedly) slightly inaccurate flight model won out over the older, though perhaps wiser MAAMSIM model. Other than wishing I could find a nice "flying the Hump" repaint for it, I have had no regrets and enjoy it thoroughly.
Again, my apologies for my big mouth, and thanks for reading...(if you did

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Deacon