Nah, Brian May is the better musician. JP is better in being a technical virtuoso, but May is a better creator of music, with more memorable guitar moments and creating signature sounds and licks that are instantly recognizable as Brian May. I can not really say that there is a signature JP sound, where you will recognize that he's the one playing when you hear a song that is new to you.
Yes, Brian May has his very specific signature style to his sounds and licks, but JP can do those, and more. He's a much more versatile musician, able to play anything from mile a minute shredding, to thick, chunky riffs, to weeping, soulful solos, to mellow acoustic stuff. I really don't understand how that makes him a worse musician. Obviously you're well within your rights to like one over the other as you see fit. But I judge musicians on their skill level, not what most people think, or how much of a cultural impact they had. I mean, The Beatles are the highest selling band in history, last time I checked, and they had so much more of an impact than DT, so I guess Ringo Star was a better drummer than Mike Portnoy, right?
What? I am not even arguing for cultural impact. So that Ringo Starr and Mike Portnoy stuff is not even close to what I am arguing.
The only thing that JP I think really has a distinct advantage over May is the shredding but that was never his preffered arsenal anyway. Let's see some of the amazing May examples in the other departments that you mentioned:
Amazing riffs - Ogre Battle, Tie Your Mother Down, Hammer to Fall, The Hitman, Now I'm Here, One Vision, Bohemian Rhapsody, Tear It Up, Keep Yourself Alive, Sheer Heart Attack (simple, but sweet), Fat Bottomed Girls, Let Me Entertain You, More of that Jazz, Death on Two Legs, Innuendo, Tenement Funster
Weeping, soulful solos - Bohemian Rhapsody (just this one already settles the matter.
), Save Me, Somebody to Love. I Can't Live Without You. And the ultimate weeping solo, The Last Horizon, where astrophysicist Dr. Brian May was on full guitar god mode.
https://www.youtube.com/watch?v=frube9ra07Y (not a complete version, the best vid of a live performance has been taken down)
Other solos - just about everything really. I especially love Hammer to Fall and We Will Rock You
And the amazing sound effects in Get Down Make Love that was so ahead of its time, people actually thought they were using synthesizers.
Mellow acoustic stuff - Too Much Love Will Kill You. The concert version of Love of My Life.
You know, musical composition is part of musicality too, and May, I honestly believe, beats JP in that department. He composes guitar parts better.