I’ve got both, both have their uses. Radar is great for navigation, collision avoidance in daylight and fog. If you e lost your GPS signal I can tell you’ll be glad to have radar on board!
I’ve got Emtek AIS transponder and a separate splitter. I take the NEMA2k output and it goes into my SIMNET backbone which is also NEMA2k just a different connector….
If you’re going Radar route, learn how to use it…. Learn how to use it in good conditions and when fog comes down you know what to do…
Things like a variable range marker is invaluable for me as worh high level of commercial traffic in Milford Haven I can set a marker as the as to how close to get to vessel. One glance at the screen and I can tell if helmsman/helmswoman is getting too close….
It’s also useful for secondary navigation, I can take a bearing off a cardinal marker and a range, and cross check on my GPS… useful for then your GPS packs up (I lost my puck signal twice so yes it can happen….)
AIS is easier to use, there is a little boat icon on your screen, keep clear of it 🤣 but everyone can see where your fishing….
If if were me, I’d go Radar and then AIS but not my cash….