Question: Which musician in known pimarily for his work with his band, John Mayer or Tom Johnston?

Context paragraphs:
John Mayer: John Clayton Mayer ( ; born October 16, 1977) is an American singer-songwriter, guitarist, and producer.  He was born in Bridgeport, Connecticut, and raised in nearby Fairfield.  He attended Berklee College of Music in Boston, but disenrolled and moved to Atlanta in 1997 with Clay Cook.  Together, they formed a short-lived two-man band called Lo-Fi Masters.  After their split, Mayer continued to play local clubs—refining his skills and gaining a following.  After his appearance at the 2001 South by Southwest Festival, he was signed to Aware Records, and then Columbia Records, which released his first EP, "Inside Wants Out".  His following two full-length albums—"Room for Squares" (2001) and "Heavier Things" (2003)—did well commercially, achieving multi-platinum status.  In 2003, he won the Grammy Award for Best Male Pop Vocal Performance for the single "Your Body Is a Wonderland".

Tom Johnston (musician): Charles Thomas "Tom" Johnston (born August 15, 1948) is an American musician.  He is a guitarist and vocalist, known principally as a founder, guitarist, lead vocalist and songwriter for the rock group The Doobie Brothers, as well as for his own solo career.  His off-and-on career with The Doobie Brothers spans more than 40 years, during which time the band exhibited numerous successful styles.

Stampede (The Doobie Brothers album): Stampede is the fifth studio album by American rock band The Doobie Brothers, released in 1975.  (see 1975 in music).  It was the final album by the band before Michael McDonald replaced Tom Johnston as lead vocalist and primary songwriter.  The album has been certified gold by the RIAA.

Clay Cook: Douglas "Clay" Cook (born April 20, 1978) is an American songwriter, producer and musician who co-wrote several songs with John Mayer including "No Such Thing", "Comfortable", "Man on the Side" and "Neon".  Cook and Mayer's songwriting partnership was predominantly through Mayer's early career, as the songs he wrote with Mayer (with the exception of live releases) only appear on Mayer's first two releases, "Inside Wants Out" and "Room for Squares".  Cook and Mayer formed the band Lo-Fi Masters prior to Mayer recording "Inside Wants Out".  Cook is currently a member of the Zac Brown Band and was formerly a member of the Marshall Tucker Band and Y-O-U.

The Village Sessions: The Village Sessions is an EP released by artist John Mayer on December 12, 2006.  Collaborators include John Mayer Trio members Steve Jordan and Pino Palladino, along with Ben Harper, Robbie McIntosh, and Ricky Peterson of Mayer's touring band and former producer for Prince albums.  The six-song EP contains acoustic and alternate versions of songs found on Mayer's third studio album, "Continuum", and his trio's live album, "Try! ".  Mayer co-produced the album with engineer Chad Franscoviak.

Where the Light Is (John Mayer album): Where the Light Is: John Mayer Live in Los Angeles, commonly referred to as Where the Light Is, is a live album and concert film by American blues-rock musician John Mayer.  Released on July 1, 2008, the album documents Mayer's performance at the Nokia Theatre at L.A. Live in Los Angeles, California on December 8, 2007, during the promotional tour for his 2006 third studio album "Continuum".

John Mayer Trio: The John Mayer Trio is an American blues rock band that formed in 2005.  Comprising singer-songwriter and guitarist John Mayer, bassist Pino Palladino and drummer Steve Jordan, the band has released one live album, "Try! " in 2005.  Three of the songs on the album were co-written by Jordan, Mayer, and Palladino, and the album was co-produced by Mayer and Jordan.

Livin' on the Fault Line: Livin' on the Fault Line is the seventh studio album by the American rock band The Doobie Brothers, released in 1977.  It is one of the few Doobie Brothers albums which did not produce a hit (although "You Belong to Me" was a hit as recorded by co-author Carly Simon).  Still, the album received modest critical acclaim.  Tom Johnston (guitar, vocals) left the band early in the sessions.  He is listed as part of the band (appearing in the inside group photo) but appears on little or none of the actual album; despite writing and singing five songs during the sessions for the album, they were not included on the final release.  Much of this consistently mellow album has a jazz tinge, and the influences of R&B are palpable throughout.  The track "Little Darling (I Need You)" is a remake of the Marvin Gaye 1966 hit.

John Mayer 2008 Summer Tour: The John Mayer 2008 Summer Tour is a concert tour by musician John Mayer to support his third album, "Continuum".  The tour has been heavily covered by tabloids due to Mayer's relationship with Jennifer Aniston.

Long Train Runnin': "Long Train Runnin'" (or "Long Train Running") is a song recorded by The Doobie Brothers and written by band member Tom Johnston.  It was included on the band's 1973 album "The Captain and Me" and released as a single, becoming a top 10 hit on the US "Billboard" Hot 100, peaking at number 8.

Supporting paragraphs: John Mayer Tom Johnston (musician)
Answer: Charles Thomas "Tom" Johnston