When I first got into guitar, Ray Toro and Frank Iero from My Chemical Romance. Frank's got some killer riffs and Ray had a really good sense of melody that a lot of the punk/emo guys didn't have. When I started playing more seriously, I jumped really fast from punk to prog and got really into Mark Holcomb from Periphery, because his phrasing and especially his riff-writing is insane.
After a while I got into (relatively) less heavy stuff, with Yvette Young from Covet, Rabea Massad (the one with the really good youtube channel) for his Toska stuff, and Mark Knopfler.
Nowadays, top five in no particular order, probably:
Fredrik Thordendal from Meshuggah for his nuts solos
Adrian Smith who has the most godly lead tone of all time and I will fight people on this
Joey Rubenstein from Icarus the Owl for showing me that prog =/= heavy and serious and deep all the time
Michael Weikath for being the most underrated member of Helloween and IMO one of the best rhythm guitarists in power metal
Brent and Ian from I the Mighty (particularly for the self-titled, Hearts and Spades, and Karma Never Sleeps EPs as well as the Frame trilogy which are some of the best post-hardcore I've ever heard) because they're absolutely killer songwriters.
Honorable mention to Steve Harris who's my Bass Daddy and will have a special place in my heart always