Work for MS for just one year with the least amount of effort possible as can be seen with their current XB1 efforts, then quit and retire off my one year CEO salary and bonus. Then ponder for the rest of my days what it would be like to be CEO of Nintendo or Playstation.

Microsoft: Halo RPG like Mass Effect, revive 1st party output, create new big IPs

Nintendo: maybe sell themselves to/partner with Apple or Disney and make a console. A big name like those will help them succeed again

Sony: doesn't need much fixing

I will choose Nintendo to form a Japanese alliance with Sony in which the two companies will create the PS5 together and support the Switch and Switch mini as the only mobile device. Together we will eradicate the Xbox brand from the face of the earth and take over the world.

Nintendo will develop all their console games exclusively for the very powerful PS5 (and Steam) while all mobile games will be released on Switch and Android / IOS simultaneously. Shares will rise to an all-time high as the financial outlook never looked so good in the history of the company.

Nintendo:
-buy Capcom;
-start hiring new developers at a faster rate to make the company bigger so that we can handle better the large ammount of IPs we have;
-Request SE a porting of KHIII and FFVII Remake on Switch;
-Request Atlus a Persona 5 porting;
-pay Rockstar for a GTA V and a RDR2 porting on Switch;
-in a few years start contracting with SEGA to buy the Bayonetta IP

Well, I assume that I wouldn't be able to do too much out of line because of all of the shareholders would get pissed at me.

Probably Nintendo.
I see them as haveing big potential, thats often just left a waste.
Id love to see what nintendo looked like if I had full power to do whatever with it.

If I was Sony I think I would end up buying Square-Enix and Capcom