I'm going from long-term memory here, but they both sounded great with the right speakers. I heard the Levinson with Wilson speakers, sounded very good but didn't make me fall in love, I blame the Wilsons (earlier versions of Watt Puppies). The Rowlands, which I heard on far more occasions, both with Avalon Ascents and Duntech Sovereigns, were particularly warm-sounding (they seemed to give up something in capturing hall ambience for a more close-up, intimate portrayal of the performance and instrumental timbres) and intensely musical amps, and given the extraordinary soundstage with the Avalons (you could actually detect a curvature to the sound of a symphony orchestra on some Decca recordings) I wondered, as I recall did J. Gordon Holt at one time in Stereophile, whether the Rowlands had a slight midrange depression/suckout which caused that effect. Nothing objectionable or at all unpleasant, just slightly noticeable on a superb soundstaging speaker. That they could handle the Sovereigns' bass indicates to me they had plenty of power and bass control. So between the two, I'd probably prefer the Rowlands, but the choice depends on your tastes and speakers.
