Interesting choice as the two speakers are in broadly different camps. I've heard various Martin Logans a number of times over the years and just never been overly impressed. I find the transition in the lower midrange disjointed and hence they don't sound natural to me since this is such a critical area for voice and most instruments. (Interesting how many times I've been told by salesmen that ""they've fixed that in the new models" only to find my experience repeated.)
I've only heard Sonus Fabers a few times but, while they aren't my first pick, I've found them quite listenable and more natural sounding than MLs.
But, MLs certainly have their following. Speakers are a highly personal choice -- given 10 speakers to choose from and 100 listeners, you're going to find advocates for every one of the 10 with other people denigrating the same speaker. There's no substitute for making your own decision.
