I have both the Reefbot and the Trident. I've had the Reefbot for a year. It's fantastic. More flexible than the Trident in terms of testing frequency and types of tests. The vials need to be filled s little too frequently and the tests take a long time to run but that doesn't matter since you set it on a schedule and forget it.
The Trident is much more accurate and specific to the big three. A different beast.
Ultimately, the best option is both, if you can afford it. With both, you can test Alk, Cal, Mg, Ammonia (Geisemann), Nitrite (Tropic Marin), Nitrate (Tropic Marin), and Phosphate (Red Sea) all automatically. Throw in an ICB Test (Triton , etc) every two to three months, and you have all your bases covered.
If you could only have one, I recommend the Reefbot with the following tests (ALK with Red Sea, Cal with API, Nitrite and Nitrate with Tropic Marin, and Phosphate with Red Sea.) Then run an ICB Test every month or two or three to check everything else.