It better be Nintendo's next home console >->.

I say sony, they always tried to have strongest system for each generation with the most hardware. Sometimes it suceeds sometimes it didnt

Both PS1 and PS2 where weaker than their competitors by quite some margin. Your statement is only true since PSP/PS3.

Yeah because other consoles came out 1 or 2 years latter but both consoles were more powerfull than its competitors at the time

Probably Sony. They would want to keep up the the theme they established with their hardware and they could take a calculated risk with their prices next generation, because simply put, Playstation is the strongest console brand at the moment. Also, keep in mind that Sony was conservative with the PS4 specs and prices because they didn't expect the console to sell as much as it did. Sony of course has to be little more careful and study the market well so they don't repeat their past mistakes.

Edit: I wrote this post under the assumption that PS5 would launch in 2019 or later.

Probably Nintendo's next handheld, if not then then the NX home console if it actually has "next gen" specs and isn't just a slightly overclocked PS4. 

Failing that I'd say Microsoft since they have the money to pour into a beast machine like they did the OG Xbox.

I think Microsoft realised this gen they have been outplayed by Sony and Microsoft really needed the stronger console to justify the price. US consumers will pay out more money and I feel the next Xbox will be stronger than the next playstation. I have no idea about Nintendo, their last two home consoles had terrible performance if they keep to their track record their next console will be about as powerful as the ps4/xbone but if they want to stay in the game perhaps they will launch a console with competitive performance. Nintendo are always looking for a third way something that will sell well despite having low manufacturing costs.

I voted for next Nintendo Console even if it will be almost the same whith the handheld

From a technical standpoint could be each one, but from a visual standpoint Nintendo, since the impact from let's say 0.5 to 2.0 Gflops is more impressive than form 1.8 to 4.5/5Gflops.

And some still think Nintendo can pull a new Gamecube?