Alternate Timeline: The first ever worldwide elections

[Hatman 🍁]

Biden would not be a candidate.

If there were a "capitalist party" (lol), someone like Angela Merkel would probably be a front runner.  Of course, there'd be a plethora of parties, and I doubt there would be 2 candidates who would emerge as front runners.  

Here are some possible presidential candidates/parties:

Communist: Who knows, but I'll give Xi to you
Progressive: Maybe Jacinda Ardern? Maybe you'd get a broad tent party fighting off challenges against people like Evo Morales in a primary. Joko Widodo is another possibility.
Liberal: Obama! He'd be a front runner world wide too. If he doesn't want to get back in to politics, then there's always Trudeau or Macron.
Conservative: Merkel would be the front runner here. Does Boris challenge her? This might be a big tent party like the Progressives, as you could have soft nationalists like Modi in this camp.
Nationalist: Trump or Putin, take your pick. Some others that could run include Netanyahu, Orban, Le Pen, Bolsonaro, Erdogan, etc. Does Duterte fit in this group?

My list is very Euro-centric of course. Quite possible someone from other parts of the world would run too.