Who is the character in Animal Farm that seems the most trustworthy? Am I correct?

Boxer is probably right - he represents the simple honest working man exploited by the Communists. Benjamin is the Donkey and is similarly trustworthy - he is the one that reads the name on the side of the van when Boxer is taken away. He doesn't however challenge the regime (he is too wise) so in that sense less reliable than Boxer. Napoleon is not at all trustworthy and the cat is plain lazy and votes on both sides in the election.