I am wondering: what is the most common, or most used, block cipher mode used that goes with CTS (CypherText Stealing)?
There is a NIST definition of CTS (CipherText Stealing) mode in the addendum to NISTSP800-38A.
The title of that addendum answers the question:
"Recommendation for Block Cipher Modes of Operation: Three Variants of Ciphertext Stealing for CBC Mode".
The paper is also useful to understand that there are many different ways to do ciphertext stealing.