Question: Which vocalist was part of more bands, Spencer Chamberlain or Donnie Van Zant?

full_context: Document 1: Johnny Van Zant: John Roy "Johnny" Van Zant (born February 27, 1959) is an American musician and the current lead vocalist of Southern rock band Lynyrd Skynyrd. He is the younger brother of the late Lynyrd Skynyrd co-founder and former lead vocalist Ronnie Van Zant, and of the 38 Special founder, Donnie Van Zant.
Document 2: Spencer Seim: Spencer Seim (born January 28, 1981) is an American musician, best known as the guitarist in the band Hella. He is also the drummer in the Nintendo music cover band called The Advantage and has a solo project named sBACH. The sticker on the cover of the self-titled release says "a thousand times better than Hella or The Advantage".
Document 3: Spencer Ludwig: Spencer Ludwig is a trumpeter, singer, and songwriter from Los Angeles, California. He is a solo artist signed with Warner Bros. Records and has also performed with Foster the People, Portugal. The Man, Fitz and the Tantrums, RAC, St. Lucia, Cherub, HOLYCHILD and The Wailers. Ludwig is also a former member of the band Capital Cities. He recorded on their platinum debut album "In a Tidal Wave of Mystery" and toured with them from 2012 to 2015.
Document 4: Thought Chamber: Thought Chamber is an American progressive metal supergroup formed in 2006. The band was formed by guitarist Michael Harris and vocalist Ted Leonard of Enchant. The band's first full-length album, "Angular Perceptions" was released in 2007 on progressive label InsideOut and received critical acclaim, including Honorable Mention from drum legend Mike Portnoy in his Top 10 Albums of 2007. Thought Chamber released their second full-length opus, a concept album entitled "Psykerion", in 2013 featuring founding members, guitarist Michael Harris and vocalist Ted Leonard, along with new drummer Mike Haid, bassist Jeff Plant, and keyboardist Bill Jenkins (Enchant). Progressive Metal web site, Grande Rock, voted "Psykerion" Best Album of 2013, and voted "Transcend" Best Song of 2013. In early 2014, Mike Portnoy invited Thought Chamber vocalist, Ted Leonard, to tour with his progressive band, Transatlantic, to fill in for Daniel Gildenlöw (Pain of Salvation) who was recovering from unexpected health issues. Ted also performed with Transatlantic, and Spock's Beard in Feb 2014 on the Progressive Nation at Sea cruise. In March 2014, InsideOut Music released the first-ever Thought Chamber video, "Transcend" which was filmed in Dallas, TX in September 2013.
Document 5: Donnie Van Zant: Donald Newton "Donnie" Van Zant (born June 11, 1952, in Jacksonville, Florida) is an American rock vocalist/guitarist. He is best known for being a member of the band 38 Special, from its formation in 1974 until 2013. He is the middle of three brothers: his older brother Ronnie was the original lead singer for Lynyrd Skynyrd who died in a 1977 plane crash in Mississippi along with five other members and associates of the band; his younger brother Johnny is the current Lynyrd Skynyrd's lead singer since 1987. Donnie and Johnny also perform together from time to time as the group Van Zant.
Document 6: Southern by the Grace of God: Southern by the Grace of God is a live album by southern rock band Lynyrd Skynyrd, this live concert was a tribute by Lynyrd Skynyrd to the members of the band who had died in the 1977 plane crash. The plane crash killed frontman Ronnie Van Zant, guitarist Steve Gaines, backing vocalist Cassie Gaines and road manager Dean Kilpatrick. This is the first album produced by the band after the '77 plane crash. The band's lineup was re-worked into a second-generation Skynyrd. The changes include: Johnny Van Zant, younger brother of Ronnie Van Zant, taking over on vocals, Ed King, who departed the band during a 1975 tour and Randall Hall, who replaced the paralyzed Allen Collins. The three (King, Hall along with founding member Gary Rossington) re-form the famous triple-lead guitar attack of the original band. New background vocalists Carol Bristow and Dale Krantz-Rossington were added to take the place of the original Honkettes.
Document 7: Mark Spencer (guitarist): Mark Spencer, (born September 28, 1957 in Champaign, Illinois) is an American guitarist, steel guitarist, engineer, multi-instrumentalist, and musician currently based in Brooklyn, New York. An original member of seminal alt-country band Blood Oranges, he continues to work as an in-demand band member and sideman with a diverse range of new and established musical artists. He is currently a member of the band Son Volt, and appears on their 2009 release American Central Dust as lap and pedal steel guitarist, keyboardist, background vocalist, and engineer.
Document 8: Lynyrd Skynyrd 1991: Lynyrd Skynyrd 1991 is the sixth studio album by American Southern rock band, Lynyrd Skynyrd, and is the first album with the new members of the band - Johnny Van Zant and Randall Hall - and the first to feature Ed King since "Nuthin' Fancy", who replaced the three who had died since the band's last release - Ronnie Van Zant and Steve Gaines in the 1977 plane crash; Allen Collins in 1990 from chronic pneumonia. This was the last album to feature drummer Artimus Pyle.
Document 9: Ronnie Van Zant: Ronald Wayne Van Zant (January 15, 1948 – October 20, 1977) was an American lead vocalist, primary lyricist, and a founding member of the Southern rock band Lynyrd Skynyrd. He was the older brother of two other rock vocalists: current Lynyrd Skynyrd lead vocalist Johnny Van Zant, and Donnie Van Zant, the founder and vocalist of 38 Special. He was the father of singer Tammy Van Zant, and cousin of musician Jimmie Van Zant.
Document 10: Team Sleep: Team Sleep is an American experimental alternative rock/post-rock group led by singer/guitarist Chino Moreno. Moreno is better known for fronting the Sacramento-based alternative metal band Deftones. Other current members include guitarist Todd Wilkinson, turntablist DJ Crook, bass guitarist/keyboardist Rick Verrett, drummer Gil Sharone and bassist Chuck Doom.
Document 11: Van Zant: Van Zant is an American musical duo composed of brothers Donnie Van Zant and Johnny Van Zant. Both are brothers of the late Ronnie Van Zant, former lead singer for the Southern rock band Lynyrd Skynyrd. Johnny became the lead vocalist for the reunited Lynyrd Skynyrd in 1987, and Donnie was also the leader and vocalist of .38 Special.
Document 12: Spencer Smith (musician): Spencer James Smith (born September 2, 1987) is an American musician. He is best known as a co-founding member and the former drummer of the rock band Panic! at the Disco. He recorded four studio albums with the band: "A Fever You Can't Sweat Out" (2005), "Pretty. Odd." (2008), "Vices & Virtues" (2011), and "Too Weird to Live, Too Rare to Die!" (2013). The band's debut album went Platinum and charted at No. 13 on the US "Billboard" 200, spearheaded by the hit single "I Write Sins Not Tragedies", which peaked at No. 7 in the "Billboard" Hot 100.
Document 13: Spencer Chamberlain: Spencer Chamberlain (born January 4, 1983) is an American musician, best known for being the current lead vocalist for the metalcore band Underoath. Before fronting Underoath, Chamberlain was the vocalist for the band This Runs Through in which his brother, Phil Chamberlain, was the drummer (who is also the drummer for To Speak of Wolves). He is currently the vocalist of Sleepwave.
Document 14: Ronnie Van Zant Memorial Park: The Ronnie Van Zant Memorial Park is a public memorial park located in Lake Asbury, Clay County, Florida. The park was built in memory of Ronnie Van Zant, vocalist of Southern rock group Lynyrd Skynyrd, who died along with numerous other band members and crew in a 1977 plane crash. The park was funded by fans and family of the band, and features a number of facilities including tennis courts, fishing ponds, a disc golf course and picnic areas.
Document 15: 38 Special (band): 38 Special (also written .38 Special) is an American rock band that was formed by neighborhood friends Don Barnes and Donnie Van Zant in 1974 in Jacksonville, Florida.
ground_truth: Spencer Chamberlain