I will agree to some extent
I believe Megadeth had better accuracy in speed.. and was more technical.... however, I prefer Metallica's solos because it FLOWED correctly....
What I mean is... Metallica is the KING of transitions... it knows which note to hit next, which note is after during a solo... and WHEN they shift the song... and do a transition between one part into another part with different rhythm or Riff, they made it seem FLAWLESS
Which is something I believe Megadeth fell short on compared to metallica.. because they have the speed and technicality, but sometimes some transitions seems OUT OF NOWHERE which did feel like it's the right flow
I hope my explaination is clear... because for example, when I listen to Metallica song, in first 1 minute, if I like it, I know I will like the rest 6 minutes... because i know whatever direction they will take, it WILL suit the song and flow right and will sound great
With Megadeth... If I liked the first minute, I was AFRAID to reach minute 4 and I don't like that part for example... because sometimes their transitions seem out of place. That's why I prefer Metallica more generally