I think people are underestimating Renault - I think they are making a very serious effort at becoming championship contenders and have a proven track record of getting it done.
Sure, much the same could be said for Honda, but Honda seems to be swimming in circles while Renault has been making steady improvement. Obviously, I think your first choice would be Mercedes/Ferrari factory teams, but if one of those 4 seats aren't up, I'm personally headed straight to the Renault tent (now that RB has committed to Honda).