Dave Mustaine
Dave Mustaine is the founding member, primary songwriter, and lead vocalist of Megadeth, as well as one of its guitarists. He has been the band's consistent creative force since its inception in 1983 and has influenced the development of thrash metal.
Marty Friedman
Marty Friedman was the lead guitarist for Megadeth from 1990 to 2000, contributing to albums such as Rust in Peace and Countdown to Extinction. He is known for his neoclassical metal style and his unique phrasing that blended well with the band's thrash metal roots. The best in technique (talking about his work in Megadeth) after Broderick in concerts. The best of all in composing and originality.
Best rhythm guitarist for Megadeth: Dave. But when it comes to solos, Marty is the man, followed by Poland, Broderick, and Loureiro.
Marty is God. Even though he denies it, he can clean the floor with any guitarist with his sweeps.
Chris Broderick
Chris Broderick was the lead guitarist for Megadeth from 2008 to 2014, performing on albums such as Endgame and Th1rt3en. He is recognized for his technical proficiency and classical guitar background. The guitarist at the time (2008-2013), and he gained quite a following quickly. Definitely a virtuoso, but it's clear that Poland ranks higher in my opinion. I can't play I Ain't Superstitious, but in another case, I can play or match the Tornado of Souls solo. This explains why Poland ranks 2nd and not Marty. Of note is the beautiful solo in How the Story Ends.
His technique in concerts is the best and more accurate than any other Megadeth guitarist, but Friedman is better at composing solos and capturing inner feeling.
Chris Poland
Chris Poland was Megadeth's lead guitarist in the mid-1980s, playing on the albums Killing Is My Business... and Business Is Good! and Peace Sells... but Who's Buying?. His jazz-influenced playing brought a distinctive sound to the band's early thrash metal style. His sense of jazz and blues is unmatched. Not even Marty or anyone else could match his style.
Sick solos. The most raw player.
Kiko Loureiro
Kiko Loureiro joined Megadeth in 2015 as the lead guitarist and played on albums like Dystopia, which won the band a Grammy Award. Prior to joining Megadeth, he was known for his work with the Brazilian metal band Angra. The most complete musician of the bunch. Just listen to his work on Dystopia.
The most technically skilled of the bunch.
Best Megadeth guitarist after Marty Friedman and Chris Poland.
Glen Drover
Glen Drover was Megadeth's lead guitarist from 2004 to 2008, during which time he played on the album United Abominations. Before Megadeth, he was a member of King Diamond, and he contributed to a revitalized period in the band's career. His playing is unique, and I liked the way he played the solos, almost as if he wrote them himself. He didn't just play what was written. He played what he was born to play.
Jeff Young
Jeff Young was the lead guitarist for Megadeth during the recording of the 1988 album So Far, So Good... So What!. His tenure with the band was brief but significant, contributing to Megadeth's growing success in the late 1980s. His style is similar to Glen's, but not the same. He had a short stint with Megadeth (1988-1989).
Al Pitrelli
Al Pitrelli served as Megadeth's lead guitarist from 2000 to 2002, contributing to the album The World Needs a Hero. He had previously worked with bands such as Savatage and Alice Cooper before joining Megadeth. His time in Megadeth was short, but the solo in Dread and the Fugitive Mind is beautiful.
Kerry King
Kerry King, guitarist of Slayer, briefly played with Megadeth during their early shows in 1984. Although his involvement was short-lived, it helped establish Megadeth's presence in the metal scene. He's a great guitarist, and his work with Slayer is impressive, but his time in Megadeth was only a week.