The thanks offering is particularly beloved because it is offered voluntarily, out of a desire to give thanks to God.

And the sin offering would come to atone for specific unwitting actions…a burnt offering would come to atone for improper thoughts…but when the thanks offering comes, it comes for no particular reason. The Holy One, blessed be He, said: This thanks offering is more beloved to Me than all the other offerings. (Tanĥuma [Buber], Tzav)