I think I should study Shiva Tattva, Vishnu Tattva and Jeeva Tattva to resolve this. Source: https://iskcondesiretree.com/profiles/blogs/lord-krishna-s-64-qualities (As enumerated in Bhakti Rasāmṛrta Sindhu (Nectar of Devotion) by Srila Rupa Gosvami, a disciple of Chaithanya Mahaprabhu) (also stated here: https://vaniquotes.org/wiki/Krsna_has_sixty-four_transcendental_qualities)
Also, there is the idea that Prabhupada said Jesus and Allah are equal to Vishnu, but Shiva is not the Supreme Godhead. But others say that he only said that under Vaishnavism, Jesus, Allah and Shiva are all understood to be descriptions of the Godhead, but to them Krishna is the biggest Godhead.
Now I’ve seen Hare Krishna pages saying Shiva Tattva is only 84.375% of the Krishna Tattva, while Jeeva Tattvas are at most 78.125%. In that sense, this could be seen as a hierarchy. But then, it could simply be a comparison of Godhead Tattvas. But then, they say Krishna has 64 Tattvas, and Vishnu has only 60 (93.75%), while Shiva has 54 and Jeevas have 50. So certainly, these are just comparisons of Godhead Tattvas. So they would even consider Vishnu to be an expansion of Krishna, and so Vishnu would not be the Godhead too.
Now it is argued that Prabhupada had to become a Madhyama Adhikaari to teach, and that is the reason for his critique of others: https://dasadas.com/2024/11/26/is-srila-prabhupada-insulting-lord-shiva/
Room Conversation — July 10, 1976, New York: Prabhupāda: According to ISKCON, Kṛṣṇa is the same God worshiped as Jehovah, Allah and so on.” That is the explanation of who Kṛṣṇa is.
Lecture on BG 9.15 — New York, December 1, 1966: God is supreme. Nobody can God. Nobody can be equal with God. God is called in the Vedic literature, asamaurdhva. Asama means nobody’s equal to Him. And nobody is higher than Him. Ūrdhva means higher. Nobody can be higher than God, and nobody can be equal to God. Everyone is lower than God, however great he may be. And there is a nice verse, śiva-viriñci-nutam (SB 11.5.33). Śiva-viriñci. Śiva means the Lord Śiva, and viriñci means Lord Brahmā. They are considered to be the topmost demigods in this material world. So they also offer their respectful obeisances to Viṣṇu, or God.
Conversation with Professor Hopkins — July 13, 1975, Philadelphia: Prabhupāda: Yes. Lord Śiva means you get material opulence but not salvation.
Shaiva Affirming
1. Shiva is Supreme
1. 18th Shloka of Shiva Sankalpa Suktam, a Khila (Supplementary) Sooktha, to be before Rg Veda 10.167:
परात्परतरो ब्रह्मा तत्परात्परतो हरिः ।
तत्परात्परतो ईश तन्मे मन शिवसंकल्पमस्तु ॥ 18 ॥Greater than the great is Brahma, greater still than that great one is Hari, even greater than this one is Isha (Shiva).
Now, the first 6 Mantras of this Sooktha are included in the Vajasaneyi Samhitha of Shukla Yajurveda (cited in reference 2 below). Note a] shows how Shaunaka’s Brhad-Devatha explains the association of the Rg Veda Mandala to the Khila Sookthas. Note b] explains the different manuscripts containing the Mantra, and this verse would be from one such manuscript containing more than 18 verses. Note c] explains the same thing as b], but in a more readable format. In Note d], I list a larger 39 verse edition I found online.
NOTE
a] Source for it being before RV 10.167: Brhad-Devatha by Shaunaka, 8.69 (Archive.org).
b] About the Shiva Sankalpa Soothra in Manuscripts (from Sayana Bhaashya of Rg Veda Samhitha, Khilani (Supplementary) section’s preface, as published by Vaidika Samshodhana Mandala):
The Sivasamkalpasukta (Yenedam IV. 11) which seems to be absent in the Alwar MS., is found in the Junagadh MS.
[…]
Khila IV. 11 is the Sivasamkalpopanisad coming after RV. X. 166. In the Kashmir MS. it consists of 13 verses. The same hymn has 28 verses in a MS. of Rgveda Samhita, No. Add 5351 in the British Museum, London. All the 13 verses in the Kashmir Khila are covered by the Khila in the British Museum MS., though in a different order. The Khila with the same 28 verses with identical text is also found in another MS., No. 2131 in the India Office Library, London. Srheftelowitz has published the text of the 28-versed Khila along with notes and German translation. T have reproduced it in the notes to the shorter Khila in the Kashmir MS. This larger version of Sivasamkalpopanisad is also found in the Junagadh MS. The Aundh edition also gives the same Khila of 26 verses, some of which are different from those in the British Museum MS. The order of verses in the Aundh edition as well as the variants in the same are also recorded in the notes to the same.
c] Also see (a simplified explanation of the above): https://www.quora.com/Is-Shiva-Sankalpa-Suktam-also-a-Khila-Sukta-of-Rig-Veda
d] I also found a different version with 39 verses, titled the Shiva Sankalpa Upanishad here (from Shri Ajnaneya Sthothranidhi, in Telugu): https://stotranidhi.com/en/shiva-sankalpa-upanishad-in-english/
2. Shiva Sankalpa Mantra (Verses 1-6), from Chapter 34 of Vajasaneyi Samhita (Madhyandhina Shakha) of Shukla Yajur Veda, Verses 1-6 (also included in Chapter 1 of Rudra-Ashta-Adhyaaya derived from Shukla Yajur Veda):
यज् जाग्रतो दूरम् उदैति दैवं तद् उ सुप्तस्य तथैवैति ।
दूरंगमं ज्योतिषां ज्योतिर् एकं तन् मे मनः शिवसंकल्पम् अस्तु ॥ 1 ॥
येन कर्माण्य् अपसो मनीषिणो यज्ञे कृण्वन्ति विदथेषु धीराः ।
यद् अपूर्वं यक्षम् अन्तः प्रजानां तन् मे मनः शिवसंकल्पम् अस्तु ॥ 2 ॥
यत् प्रज्ञानम् उत चेतो धृतिश् च यज् ज्योतिर् अन्तर् अमृतं प्रजासु ।
यस्मान् न ऽ ऋते किं चन कर्म क्रियते तन् मे मनः शिवसंकल्पम् अस्तु ॥ 3 ॥
येनेदं भूतं भुवनं भविष्यत् परिगृहीतम् अमृतेन सर्वम् ।
येन यज्ञस् तायते सप्तहोता तन् मे मनः शिवसंकल्पम् अस्तु ॥ 4 ॥
यस्मिन्न् ऋचः साम यजूꣳषि यस्मिन् प्रतिष्ठिता रथनाभाव् इवाराः ।
यस्मिꣳश् चित्तꣳ सर्वम् ओतं प्रजानं तन् मे मनः शिवसंकल्पम् अस्तु ॥ 5 ॥
सुषारथिर् अश्वान् इव यन् मनुष्यान् नेनीयते ऽभीशुभिर् वाजिन ऽ इव ।
हृत्प्रतिष्ठं यद् अजिरं जविष्ठं तन् मे मनः शिवसंकल्पम् अस्तु ॥ 6 ॥
NOTE
a] Rudra-Ashta-Adhyaaya has 10 chapters (8+2 supplementary). The first chapter has 10 verses, and the last 6 of them is the Shiva Sankalpa Sooktha. Chapter 2 includes the Purusha Sooktha from Rg Veda again. b] This is the same in Ralph TH Griffith’s translation in sacred-texts.com. But that version translates too much that it is unreadable.
3. Krishna Yajur Veda, (Taittiriya Shakha) Taittariya Aranyaka 10.12:
यो देवानां प्रथमं पुरस्ताद्विश्वाधिको रुद्रो महर्षिः ।
हिरण्यगर्भं पश्यत जायमान स नो देवः शुभयास्मृत्या संयुनक्तु ॥ १२॥He who is the first among the Gods, that Rudra who is the great seer who is higher than the Universe (VishwaAdhik), he is the one who saw Hiranyagarbha being born.
4. Krishna Yajur Veda, (Taittiriya Shakha) Taittariya Aranyaka, Chapter 10 (Mahaa Naaraayana Upanishad / Brihan-Naaraayana Upanishad), Verses 24.1 and 25.1:
सर्वो वै रुद्रस्तस्मै रुद्राय नमो अस्तु । पुरुषो वै रुद्रः सन्महो नमो नमः । विश्वं भूतं भुवनं चित्रं बहुधा जातं जायमानं चयत् । सर्वो ह्येष रुद्रस्तस्मै रुद्राय नमो अस्तु ॥ 24.1 ॥
कद्रुद्राय प्रचेतसे मीढुष्टमाय तव्यसे । वोचेम शंतम हृदे । सर्वोह्येष रुद्रस्तस्मै रुद्राय नमो अस्तु ॥ 25.1॥
All this verily is Rudra. To Rudra who is such we offer our salutation. We salute again and again that Being, Rudra, who is Purusha. The material universe the created beings and whatever there is manifoldly and profusely created in the past and in the present in the form of the world, all that is indeed this Rudra. Salutations be to Rudra who is such. We sing a hymn that confers on us happiness in the highest degree to Rudra who is worthy of praise, who is endowed with the highest knowledge, who rains objects to the worshippers most excellently, who is more powerful and who is dwelling in the heart. Indeed all this is Rudra. Salutations be to Rudra who is such.
NOTE
a] Shloka 25.1 above contains Shloka 1.43.1 of Rg Veda b] This is a Vaishnava Upanishad, but glorifies Naaraayana and Rudra
5. Shiva Sankalpa Sooktha from Shaiva Upanishad:
A 37 verse version from the Puraanas is here: https://www.sanatangroup.org/shiv-sankalpa-upanishad/6905/
Vishnu Affirming
They use verses from Padma Purana and so on.