This is one of those jokes on the internet that I dont get right?

Microsoft, easily. Nintendo are on far stronger footing than previous years and likely have both Smash Bros and Pokemon launching this year. Sony are still the clear market leader and similarly to Nintendo, have a slate of guaranteed hits coming up.

Microsoft have done good work improving Xbox One, but they still lack distinctive, killer software, and are struggling (globally) against PS4 and now Switch. They need to come out swinging and don't seem to have any major cards to play right now - so confirmation of something like Halo 6 or other major exclusives is more important for them. Sony and Nintendo are likely to hunker down around the exclusives they already have as a way of cementing their current momentum; it's Microsoft who need to swing the pendulum in their favour.

Sony: they could pretty much announce nothing and still a release lineup to rival Nintendo

Nintendo: similarly also have several announced but as of yet unseen, and just reminding people if said games should be quite enough

MS: going into this year they seem really quiet. No "Greatest lineup in XBox history", no "42 """exclusives""""" rubbish. This, coupled with recent studio closures and their own statements (the economics of single player games are complicated, guys!) seems to indicate they don't have much.

MS needs to show freaking games, or wrap it up and go home. for me its halo 6 or fuck off. though a new gears and horizon are going to be day one, its not what i want most, halo, the reason i have an xbox.

Sony just needs to cruise control thorough it, the fans will see most of what they want, whether it comes out in 2-5 years is another question for later. I expect a GoW DLC of sorts, like they did HZD.

Nintendo, welp nintendo, I dont care for reggie at all. I have watched their e3 presentations until last year or the year before, its been awhile and doesnt matter, it works better for me to see what they announced and pick and choose what to watch.

Hasn't E3 been irrelevant since mid 2000s when the internet went into masses?

Nintendo stopped being dependent when they started directs. People now know that if E3 isn't loaded for them, it's because in a couple of months they will have a direct with just as big of games and still launching this year.

Microsoft has 3rd party games and not a whole lot else at and they don't do the direct system so if I had to rank importance for E3 in terms of which company needs it most I'd say

1. Microsoft
2. Sony
3. 3rd party publishers.
4. Nintendo

 Somebody’s been drinking a lot of haterade. God of War still got you down? Also, TLoU2 and Death Stranding will be two of Sony’s front runners this year, and they both feature multiplayer. Learn to read. 

God of War with the extras is like 30hours... if you want to 100% it, its like 50hours.
Also its 60$... plus theres something to be said about quality.

Would you rather play a multiplayer online shooter, with a "meh" experiance, that  you can play for months if you want too, or a single player that ll give you a insanely good 30hours? Some people value the "experiance" over the time you can spend on a game.

For me it is quite obvious that it's Nintendo.

Sony is in a steady good pace that independent of E3 as far as we can see.
MS won't improve much doesn't matter what they show on E3.

Nintendo is early in the gen, have a lot of potential sales, and great IPs that are to make the first show on Switch and all that could drive sales a lot.

For those reason this E3 have more importance for Nintendo than to the other 3.

Sony doesn't appear to really need a great E3 for all the reasons said by others.

Nintendo does need a great E3, if only because they have told their investors they want to ship 20m units this fiscal year, so they have put pressure on themselves to deliver a huge year.

From a gaming perspective, MS does need a great E3, for the reasons said above. On another level, Xbox is a very small portion of Microsoft's overall business, so I doubt Satya Nadella (MS's CEO), is all that concerned about E3.