If one was really better than the other Mesa would discontinue or improve the other and make them sound identical...
Anyway... you get the point.
It's totally subjective. I'm an older guy and I prefer vintage sounds... I like and appreciate really good sound quality. Matchless, Bogner, and Badcat are some of my favorite sounding amps. I think what it comes down to more than anything is your playing style and the type of guitars you play. Certain platforms excel for different styles. Also personal preference comes into play. I've played through the MKIV, Lonestar Classic, F50, F30, Rectoverb, Stiletto Ace, Stiletto Deuce, and the Lonestar Special. What I heard from the Special earned it last place among these amps. I would take an F30 over it! Does that mean the F30 is a better amp? Absolutely it does! To me. I found the Lonestar Special had terrible high gain. Does that make it a bad amp? It does for someone like me who prefers more gain but for others who like it more bluesy and play single coils it may be perfect! It also depends on what tubes you prefer. Personally I've never liked EL84 based amps. Others wound play nothing else. Best way to find out is to go play through them and see which amp your guitar, fingers, and ears like the best... because one thing I know is that it will likely be different than what everyone on this thread is telling you. You might prefer a Matchless!