General Hesitation:
* Unwilling
* Disinclined
* Averse
* Loath
* Leery
* Dubious
* Apprehensive
* Wary
* Hesitant
* Ambivalent
Reluctance Due to Fear or Dislike:
* Afraid
* Apprehensive
* Dreading
* Reluctant
* Uncomfortable
* Resistant
* Resistant
* Repugnant
Reluctance Due to Lack of Enthusiasm:
* Indifferent
* Apathetic
* Uninterested
* unenthusiastic
* Tepid
* Half-hearted
Reluctance Due to Feeling Forced:
* Coerced
* Compelled
* Obliged
* Pressured
More Formal/Literary:
* Disposed
* Reticent
* Unresponsive
* Demurring
* Inclinable
The best word to use will depend on the specific context and the desired tone.