It's a common observation that when a gaming company is at the top that they tend to get kind of....stupid. Arrogant even. They tend to be morons or do things that backfire on them. 

Everything from the PS3 to the Kinect Eye of Sauron to Software Total Restrictions and many other incidents in between, we've seen this from all three at one point or another. 

(Because the Seventh Generation is weird and I think at least two companies, if not three, have been claimed to have won it) 

However who is the most insufferable when they are at top? Who lets their ego get a bit over the top? Etc etc? 

(Not sure if this is something to answer as it is for the company, us as the customers, some third thing, or it all in general. Worth specifying in response I think)

They are all as bad as each other when they are at the top

Its why competition as good, they have to first be the worst and try to be good to get to the top to become the worst

Well, to be fair MS has never been "on top" per se.

Anyway, to answer the question I'm going to vote MS despite not being the market leader. But this is with very limited data. MS botched the Xbox One launch HARD. Now, Nintendo faltered with the Wii U, but it was more because of an inability to advertise correctly and a misunderstanding of market direction. Sony botched the PS3 launch, but that was mostly because of the hardware they were trying to sell (they launched with full BC and everything). MS is really the only one that I feel was truly complacent.

This.

I'd say Nintendo. If it wasn't for Nintendo's huge ego at the time from being so on top of the gaming industry and trying to destroy Sega, there wouldn't be a PlayStation Nintendo has no problem lawyering up if you try to mess with their IP in any way shape or form, and now with the Switch's success, they've engaged in the practice of charging for online play with crappy functionality, cloud saves, and infinitely monetizing their legacy games.

Not to mention how insanely stubborn they are. When Sony gets crap from the community for attempting to shutdown the PS3, PS Vita, and PSP stores, they reversed course. Minus the PSP. When Nintendo gets crap from the community for shutting down the Wii U and 3DS stores, they'll go "meh"

And those are just some examples off the top of my head. 

The Nintendo PlayStation thing was doomed from the start. Sony and Nintendo both wanted things that were unreasonable to each other. But ultimately yes it was Nintendo who cut the rope. 

Sony also has a similar online structure that makes you pay for cloud saves so I don't know why that's a point to make. Also Sony still closed down the PSP store. It has been that way for a while now. They will also eventually close down the Vita and PS3 stores. Nintendo was just the only one to stick to their anti-consumer guns while Sony just wanted to temporarily reverse course due to optics. Once they implement the new online tiers that include legacy titles, the PS stores will close. This is why the wanted to close them in the first place. 

Let's not act like any of these companies are better than another because their goals are all the same. Make money. You're just a number to them. An account ID with money. They all lie, they all pull anti-consumer practices. And even if you think they're "listening" they're just saving face until the right time comes. 

I disagree.  I have stated before I like MS as the underdog and working in last place then first because they definitely try harder then both Nintendo and Sony but MS has never been in the top spot.  All of them had one bad season for their consoles but only Sony and Nintendo gets the advantage of people letting it go.  MS on the other hand is always viewed in a different light and under more scrutiny.  When MS screwed up, they got rid of the problem pronto, when Sony and Nintendo screw up, they continue as usual.

I wouldn't consider Microsoft to have ever been at the top, unless we aren't talking about gaming.  Man, you don't even want to know what they did to Netscape.  However, there has been a third company at the top: Atari, and they are far worse than either Nintendo or Sony.  They are responsible for crashing the console market in the US.

As far as Nintendo vs. Sony, I kind of think Nintendo is both awesome and terrible at the top.  All of their top selling consoles have been great.  Nintendo is at their best when they reach the top through innovative new games and/or hardware.  However, their devs also get really big egos and then often start to do stupid things which lead to failures (Virtual Boy, N64, Wii U, etc...).  Sony, on the other hand, is not great but not terrible either.  They stay fairly consistent at the top, but they don't really innovate much IMO, and occasionally their consoles can get too pricey.

I'm going to disagree that they try harder than Sony and Nintendo. I'm also going to disagree about your perceptions regarding Nintendo and Sony "going on as usual". Microsoft's biggest misstep was a software issue (online drm). Which they still haven't quite fixed as the Series product line still requires an internet connection to set up for the first time where Switch and PS5 do not. MS instead pivoted and went for improved image. They stopped talking about always online and pivoted to BC and eventually Gamepass. MS fixed some things too (i.e. removing Kinect to decrease price, better hardware in series consoles), but similar things have been done with Nintendo and Sony consoles in the past (N64 and GameCube slashed their prices significantly, then you have 2ds, PS3 removed BC in order to lower the price, created ps+ to improve online play). Sony and Nintendos missteps have been mostly at the hardware level or even naming conventions (Wii U instead of Wii 2). You can't just change the entire technical specifications of the console. You have to ride it out.

I'm also going to disagree with MS being under more scrutiny. Series X, 360, and original Xbox were all praised quite heavily. 

Microsoft.