Agree with Searun. I installed the Garmin Reactor 40 last spring and it's been great. Makes all the difference when setting or checking lines. Now if it could just steer around debris in the water automagically, I'd really be set!
Based on my limited experience to date, I would recommend getting the autopilot from the same manufacturer as your chartplotter/radar. I originally purchased the Raymarine autopilot as many had spoken favourably about it. It was slightly less expensive than the Garmin & I knew I could connect it into my existing NMEA2K network with an adapter. However, the Raymarine S100 remote control option (which I wanted so I could steer from the stern) is based on their original Seatalk 1 protocol (proprietary NMEA 0183) that is about 30 years old. It was designed to control Raymarine's original autopilots released in the 90's and the only thing they have changed since then is the selling price. The new Raymarine evolution series autopilots were released in 2013 based on the SeatalkNG protocol (proprietary NMEA2K) but they never released a new remote control. Instead, you need to purchase a Raymarine conversion kit to convert the very simple legacy remote (that costs $500 CAD) from Setalk1 to SeatalkNG. The conversion kit is another $140 CAD. This is not advertised ... not even in the remote control installation instructions does Raymarine reference anything about a conversion kit. But once you lay out the equipment for the install, it's clear there is no path to making that remote control work. Once you search online, it becomes apparent that a conversion kit is required to make the new $500 remote work with the new Raymarine autopilot. It makes for a messy install & I was annoyed at the idea of having paid that much money for a remote that needed a conversion kit to work. Rather than deal with the extra cabling and cost of the conversion kit I sent it all back and went with Garmin to match my system. The Garmin remote was less than $400 and wirelessly connects to the chartplotter so no additional cabling required. Very clean install. And it is far more advanced with a built in directional compass .. so you can just point in the direction you want to go and click and the autopilot steers on that heading. If you have a Raymarine system already, sticking with Raymarine autopilot is probably the best option but it is amazing to me that Raymarine invested time to design a conversion kit for an outdated remote control rather than update the remote to align with what the competition is offering.