I missed this one but have to chime in as it's my favorite music.
Jerry Cantrell over Dean DeLeo by a slim margin. Jerry is just the king of grunge riffs IMO. Go-to when you have a high gain amp and want to rip on something. Heavy, melodic, and grooving. His solos are fantastic too, not overly flashy and perfect melodies for the song. Icing on the cake is his vocal harmonies and just overall songwriting.
Dean I absolutely love. He's kind of a chameleon where he can step into heavy grunge riffs (Core) into classic rock Zep inspired stuff (Purple) into straight up jazz (Tiny Music). His leads are so memorable and well constructed, and he definitely has a style. I only put him behind Jerry because Robert DeLeo was the primary songwriter in STP for all those hits.
Others...
Kurt I love and respect as a songwriter and singer and he was a decent guitar player as well. Not ripping leads but perfect for the songs and the band. Nirvana wasn't as exciting and dangerous as they were if they had Steve Lukather. I almost certainly wouldn't have gotten into playing guitar (and drums) if it weren't for Kurt.
Kim Thayil is a really interesting guitarist and lead player and helped shape Soundgarden and early grunge. But Chris Cornell was the primary songwriter and played most of the riffs we know. He's really underrated for his guitar playing and riff writing. His voice was like a god, and his acoustic playing was fantastic too.
Billy Corgan isn't on the list and isn't quite a grunge guy but close enough. He's a fantastic guitarist, great song writer, lots of killer riffs, played pretty much all the parts. He's awesome in his own way.
Mike McCready I like but don't love. His early soloing was over the top in a fun way but you could hear him really trying to channel SRV and I think it dominated his memorable solos. After those first couple albums I honestly couldn't pick out anything he did though. Stone Gossard on the other hand wrote (I believe) almost all the great riffs and songs on the first couple albums; I respect the riffs a lot more than solos for grunge guitar. Again, after Vitalogy though he took a backseat to Eddie and the band got way too tame. I wish there was an alternate history where Stone was the lead for a couple more albums and they kept Dave Abbruzzese (although Eddie probably would have quit).
Honorable mention to Peter Klett from Candlebox though. They were tossed aside as "riding the coat tails" of grunge but they were just younger and in the right spot at the right time. The first Cbox album was awesome, a cool mashup of grunge riffs and bluesy style kind of like early Pearl Jam. But there's also a bit of 80's metal in there and you can hear sonically, it's more well produced and not like a punk rock album. The riffs on that first album were great and the lead playing is really good too, really melodic with a bit of flash.