Nope supreme essence Spirit are even rarer than body Spirit they are so powerfull that They can overcom Spirit with a element whish should Beat them (supreme ice essence would beat fire essence while ordinary ice essence wouldn't
Actually from the 2 novels, I would say that ice essence would be equal to fire essence. This is hinted at when grandmaster talks to Ma Hongjun after his battle in the ranking part of the tournament saying that fire and ice mutually countered each other. In the case of combat continent 2, fire was beating ice due to the quality of the essence, pheonix fire(top quality) vs normal ice.
Body Spirit Essence strength's depends on which part of the body it is. On MC's case it was his eyes and was one of the most supreme Body Spirit Essence.(The more important the body part, the stronger it is.) What makes it more powerful is that there is a second awakening.The strength of the Second Awakening is divided by 4 Ranks. (From weakest to strongest) Black Iron Rank Awakening, Bronze Rank Awakening(1 out of 10), Silver Rank Awakening(Less than 10 in the whole Innate Body sect), Gold Rank Awakening(MC's level).
Black Iron Rank Awakening increases the power/quality of spirit by 30%
Bronze Rank increases the power/quality of spirit by 60%
Silver Rank Awakening increases the power/quality of spirit by 100%
Gold Rank Awakening increases the power/qualiuty of spirit by 3 times/300%
So Body spirits are already rare and Gold Rank awakening are like legends. Its already comparable or even stronger than supreme spirits. Other than Body Spirits, Beast Spirits with Absolute Element/Attributes are also one of the rarest and strongest Spirits. MC's second Spirit Ice Jade Scorpion Emperor is an Absolute Ice Element spirit. It can suppress almost any elements used against it. Absolute Spirits may sometime only occur randomly or in unique cases such as Ma Xiaotao with the improvement of the quality of her Phoenix Spirit, it had Absolute Flame. As for Spirits like Clear Sky Hammer, they may be rare but not as unique as Body Spirits or Absolute Spirits because they are inherited by a bloodline of a clan. Blue Silver Emperor may also be considered unique as it can only appear in a single generation. There were also Divine Beast Spirit Essence in DD2 which are very rare and almost comparable to Absolute Spirits in strength such as Xu Sanshi's Golden Black Tortoise(Evolved from Mystic Water Turtle) and also Xiao Hongchen's Spirit Variation which became a Three Legged Golden Toad. As for the Angel Spirit, it was rare due to events of DD1 when Spirit Hall was eradicated. It was also very powerful and once it evolves into having 6-Wings, it is already comparable to Absolute Spirits. In DD1 Qian Ren Xue was already Awakened with Seraph(6-Wings) so it was already very powerful and comparable or even stronger in quality than Clear Sky Hammer. While in DD2, Ye Guyi's Angel Spirit slowly evolved from 2-Winged Angel to 6-Winged when she finally became a Title Douluo.