Well, it looks like Ricciardo is going to sign with Red Bull for two years. I actually think he would be better off with the 5 year contract at McLaren (if they are willing to sign so long...maybe 3 and options), then two years at Red Bull. My reasoning:
1. While he will get wins are Red Bull.....he will be the defacto the #2 driver, although they will claim otherwise.
2. When he goes job hunting in 2021....there will not be a lot of options because drivers like Hulkenburg, Perez, Ocon, Gasly and Leclerc will have filled up all positions worth having.
3. If he goes to McLaren for 5 (or 3 +2) years, he will not win any races in the next two years but.....McLaren will certainly come back to some degree, especially if the budget cap comes into place in 2021.
4. He potentially is leading a contending team in 2021-2023 under the new regulations and budget cap era. This is a good position to be in.
5. It is demoralizing to be a #2 and motivating to be a lead driver on a team.
6. He will also make more money.
7. Going to McLaren he at least has a slim chance of winning a WDC in the next five years. I don't think he has much of a chance otherwise.
But....I always have a bias towards taking the "road less traveled" as opposed to the obvious and safe option. It is how I have lead and mis-lead my life.