All the bickering over which system is more powerful, or has better graphics is almost completely useless. Every system generation to date has had it's winner decided by who has the most interesting unique software(and more often than not, it's the less-powerful system winning the sales battle).
NES crushed the technically superior Sega Master System thanks to the likes of Mario and Zelda.
Genesis crushed SNES through the majority of the 16-bit lifecycle(Genesis outsold SNES in America until it was discontinued in 1995, whereas Nintendo kept making the SNES for several more years, thus eventually pulling ahead in sales)despite being quite a bit less powerful
The 32-bit PS1 crushed the 64-bit N64
PS2 might be the only system that won, and was the better piece of technology, compared to the Xbox(but that comparison is subjective. PS2 is more powerful in some departments, but is the lesser machine in others. There's no real clear dominant technology in this generation)
Xbox 360 won out handily in North America over the more powerful PS3.
The PS4 being more powerful means absolutely nothing if they don't have a LOT of unique software that people want. They better have a pretty solid exclusive library built up by the time the next Halo shows up on the XB1, or they could be in trouble again.
So out of the last 5 generations of consoles, only once has the superior hardware won and sold more systems.
So many incorrect things in this post. In some sense it comes down to games, but it is not that simple.
Master System and NES were released in NA in '85, but the NES had been around since '83. So of course the technology was worse, it was two years older (though it had 5 audio channels to 4, it was worse in every other technical category). But the reason Nintendo won that generation was the small crash of '84, that put a huge number (relative to the time period) of non-Japanese developers out of business and the strict contracts that leverage allowed Nintendo to enact on third party developers. Two year restrictions on porting games, for instance. If cross-platform has been a thing that was allowed, it would not have been as one-sided, or if so many developers hadn't gone out of business right as they both were releasing overseas. Even then, the SMS was the winner into the mid-90s in Europe, Brazil, Australia, and New Zealand. The difference between the areas where SMS won and lost? The relative size of the marketing budgets. SMS won in every territory where it outspent Nintendo in marketing, despite all other factors. It didn't have a US office at all and sold the marketing rights for the US to Tonka toys, who sat on them till the contract was up. Which resulted in fun things, like Nintendo actually telling retailers they could have the NES or the SMS on their shelves, not both, and retailers put the NES up. So 8-bit generation: won by bloodthirsty business practices and marketing.
The SNES had a less powerful CPU than the Genesis. In every other category, it was more powerful. 256 colors vs 64, 128 KB RAM vs 64 KB RAM, 64 KB sound RAM vs 8 KB sound RAM, larger sprites, more layers, 32k+ colors vs 512. Again, two year gap, Genesis released in '88, SNES in '90. So of course the later released system had better specs. Sega did better this generation, making most of their market gains in (and this shouldn't surprise anyone) NA. Because they had a marketing campaign this time, including the famous "What Nintendon't" campaign. This is when Sega did something remarkably stupid, they started releasing hardware add-ons like the Sega CD and the 32X, rather than focusing on games. They went from winning with a less powerful console, to losing. Sega cost themselves the 16-bit generation.
The PS1 was less powerful than the N64. In an interesting way, Sony forgot something really important with the PS3 that they should have learned from this generation. The N64 was more powerful on paper, just like the PS3 was more powerful on paper than the 360. Reality? The N64 being constrained by the cartridge memory almost always looked worse and was harder to develop for. Both at their best? N64 looked better. But most multi-platform releases looked better on the PS1. Just like, despite the power, most multi-platform releases of the last generation looked better on the 360. Timing again played a role, with the PS1 releasing two years earlier and so already having saturation, in addition to the enormous marketing campaign.
PS2 was the better machine. The Emotion Engine was brilliant and the PS2 could do things that were only possible on dedicated graphics workstations prior. Everything being integrated and designed from scratch made an enormous difference. The only place the Xbox was even a little ahead was the sound chip. However Microsoft knew they were going to lose this generation, so their marketing strategy was about getting the brand out there, getting in-house developers, building connections, etc. It isn't even really fair to compare them, PS2 was just a money making machine, the Xbox was a sunk cost to break into a new market for Microsoft.
PS3 was more powerful on paper, but (and we learned this from the N64) being harder to develop for costs you. The 360 is very easy to develop for, especially by comparison. Though going purely by sales, the Wii won this generation, being 22 million ahead of the 360 and 25 million ahead of the PS3. Which it did with marketing. Marking itself to "non-gamers", which, in gaming, is basically an untapped market.
So out of the last five generations, marketing and business decisions (good or bad) decided all of them. By that metric, I am going to predict the PS4 wins the coming generation. In seven years it'll be 5-10 million consoles ahead of the XOne, at roughly 85 and 75 million respectively.