A basic stability augmentation system (SAS) will give you rate damping and therefore smooth out your control inputs and make the aircraft less twitchy - the downside is that you lose some of your responsiveness to control inputs.
An autopilot will give you the facility to hold an attitude, heading, speed or height depending on which inputs it receives from which sensors - this will clearly be more expensive.
For general private flying I would suggest a SAS is enough, it is when you get to IFR and similar regimes that an autopilot is useful to reduce pilot workload.
The above information is generic, I have no knowledge of the specific products for an R44.