I have done both. I worked for insurance as a case manager for worker's comp and no fault auto - those cases are long termers, meaning they are the medically complex and usually have psych components related to long term disability. It can be hard to move those folks forward and make choices, none of which are as good as they thought they had it before they got hurt. You get to know them well, but it is slow going. Often there is vocational rehabilitation and retraining planning.
Inpatient is completely different. You get a case load every day, usually with 15-20 patients or more, about 30% can be new every day give or take. Every day you field pages, work on discharge planning, handle social work issues, and in my case, include insurance reviews for which you don't really have time to deal with. Much more stress, more variety, faster paced. Sometimes you feel you are drive by case managers, because you don't have time to teach or listen much. I am supposed to see every patient within 24 hours of admission, but in reality I maybe see 5 out of 18 or 20. Some days you see only 1 or 2. Some days you can see 8 if you have no insurance reviews and no one needs anything. I would be much happier if I didn't have to deal with the insurance stuff - that is a job in itself and has no place in the case manager job, in my opinion.
It all depends on which pace is right for you. I like seeing patients and family, and helping with discharge planning tranfers; I don't like feeling like if you spend more than 15 minutes with a patient, you will get behind or get paged.
Insurance work means complications like chronic pain, disability lawyers, entitlement attitudes, and rare successful return to productive work, but it does allow a closer working relationship with patient and families.