Given a target distribution µ and a proposal chain with generator Q on a finite state space, in this paper we study two types of Metropolis-Hastings (MH) generator M 1 (Q, µ) and M 2 (Q, µ) in a continuous-time setting. While M 1 is the classical MH generator, we define a new generator M 2 that captures the opposite movement of M 1 and provide a comprehensive suite of comparison results ranging from hitting time and mixing time to asymptotic variance, large deviations and capacity, which demonstrate that M 2 enjoys superior mixing properties than M 1 . To see that M 1 and M 2 are natural transformations, we offer an interesting geometric interpretation of M 1 , M 2 and their convex combinations as 1 minimizers between Q and the set of µ-reversible generators, extending the results by Billera and Diaconis (2001). We provide two examples as illustrations. In the first one we give explicit spectral analysis of M 1 and M 2 for Metropolised independent sampling, while in the second example we prove a Laplace transform order of the fastest strong stationary time between birth-death M 1 and M 2 .