Very early to say at the moment, but based purely on the first round of tests Mercedes seem to have reliability which could be a more valuable commodity than out right speed this year.
It is very interesting how Red Bull have been writeen off at this quite early stage, despite their domination of recent years. I guess the upcoming testing session will make things clearer re. the Renault woes. I did vote Merc though - it would be good to have a change!