AIS only show you large ships and you will miss smaller boats not transmitting AIS. A modern radar with high resolution and display at the helm where can set proximity alarms is particularly useful if you are single handling or when you end up in pea soup fog, particularly near shore.
AIS does not replace a good radar!
I currently have a B&G Zeus that connects to the original autopilot via a B&G AT10 NMIA converter and plots AIS, and Radar signals
Ipanema SM2K 278