Who is greater, Vishnu, Shiv, or Bramha?

Who is greater, Vishnu, Shiv, or Bramha? Well, if we go by Mahabharata all these three deities are said to be the same and there is no difference between them. But according to Vedas, it is only Sri Rudra who is superior to Sri Vishnu and Brahma Ji. The Shiva Sankalpa Suktam clearly state it. Vedas always will have more authority than Itihasa and Puranas. Hence Vedas clearly state that Sri Rudra is superior to Sri Vishnu and Hiranyagarbha. Sri Rudra is also said to have none equal to him (TS 1.8.6.2). परा᳚त् परत॑रो ब्र॒ह्मा॒ त॒त्परा᳚त् पर॒तो ह॑रिः । त॒त्परा᳚त् पर॑तो ऽधी॒श॒स्तन्मे॒ मनः॑ शि॒वस॑ङ्क॒ल्पम॑स्तु ॥ 18 Greater than the great is Brahma, greater than the great Brahma is Vishnu. Greater than the greater Vishnu is Isha (Shiva). May my thoughts be filled with Shiva. - Rig Veda Khila, Shiva Sankalpa Suktam, 18th Mantra. Regarding the authenticity of Sri Shiva Sankalpa Suktam: