Mozart performed his Piano Concerto No. 21 in C major, K. 467, the most frequently. This concerto, known for its delightful melodies, was premiered by Mozart himself and became widely popular, especially after its second movement was featured in the 1967 film "Elvira Madigan"[2].
Sources
[1] Mozart's most beautiful piano concertos | Digital Concert Hall https://www.digitalconcerthall.com/en/playlist/30
[2] The 20 best piano concertos of all time https://www.classicfm.com/discover-music/instruments/piano/best-concertos-all-time/
[3] MOZART Piano Concerto No 20 - YouTube https://www.youtube.com/watch?v=71AgofmDSjs
[4] Most important/best and favorite Mozart Piano Concertos https://www.talkclassical.com/threads/most-important-best-and-favorite-mozart-piano-concertos.47709/
[5] What is Mozart's Greatest Piano Concerto? - YouTube https://www.youtube.com/watch?v=Pms-nFWY-nM
[6] 6 of the best Mozart concertos to add to your playlist - Classic FM https://www.classicfm.com/composers/mozart/guides/mozarts-concertos-where-start/
[7] The Classical Music Guide Forums http://www.classicalmusicguide.com/viewtopic.php?t=44225
[8] Piano concertos by Wolfgang Amadeus Mozart - Wikipedia https://en.wikipedia.org/wiki/Piano_concertos_by_Wolfgang_Amadeus_Mozart