Doing Deity worship, going on pilgrimage, chanting mantras, and performing rituals is good, but preaching is far more important so that others can benefit too.

  • Preaching is purely thinking of Krishna (the purpose of chanting) and most pleasing to Him, because others will also benefit. 
  • Preaching is worship of Lord Krishna (the purpose of Deity worship), because it involves studying the Bhagavad-Gita and distributing the knowledge to others, this is real proof of not being self-centered.
  • Preaching is real service to others, because they too can know God as a person (Lord Krishna), engage in His service, attain His love, and go back to the spiritual manifestation and live eternally in complete bliss in the same spiritual body at the end of this short life.

“And I declare that he who studies this sacred conversation of ours worships Me by his intelligence.” (Lord Krishna, Bhagavad-Gita 18.70)

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Shrimad-Bhagavatam 7.14.40:

Translation
Sometimes a neophyte devotee offers all the paraphernalia for worshiping the Lord, and he factually worships the Lord as the Deity, but because he is envious of the authorized devotees of Lord Visnu, the Lord is never satisfied with his devotional service.

Purport
Deity worship is especially meant for purifying the neophyte devotees. Actually, however, preaching is more important. In Bhagavad-gītā (18.69) it is said, na ca tasmān manuṣyeṣu kaścin me priya-kṛttamaḥ: if one wants to be recognized by the Supreme Personality of Godhead, he must preach the glories of the Lord. One who worships the Deity must therefore be extremely respectful to preachers; otherwise simply worshiping the Deity will keep one in the lower stage of devotion.

“Do not come to Jagannātha Purī every year, but stay in Bengal and fulfill My desire.” (Lord Caitanya, CC Madhya 16.64)

“Preaching Caitanya Mahāprabhu’s cult throughout the world is more important than staying in Vṛndāvana or Jagannātha Purī for one’s own personal satisfaction. Spreading Kṛṣṇa consciousness is Śrī Caitanya Mahāprabhu’s mission; therefore, His sincere devotees must carry out His desire.” (Purport by Swami Srila Prabhupada).

Letter by Swami Srila Prabhupada to Sri Govinda (06dec1974, Bombay):

Book distribution is bhagavata marga and temple worship is pancaratriki viddhi. Both are important for cultivating Vaisnavism but comparatively speaking bhagavata marga is more important than pancaratriki viddhi. As far as possible both should go on in parallel lines but still bhagavata marga is more important than the other.

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The Highest Service Unto Lord Krishna 

“One who liberally disseminates this knowledge among My devotees is the bestower of the Absolute Truth, and to him I give My very own self.” (Lord Krishna, SB 11.29.26 – Bhakti-yoga chapter)

“For one who explains this supreme secret to the devotees, pure devotional service is guaranteed, and at the end he will come back to Me. There is no servant in this world more dear to Me than he, nor will there ever be one more dear.” (Lord Krishna, Bhagavad-Gita 18.68-69)