The most frequent triad I grab is still this one. Adding extensions, suspending the third, or even dropping the root in favor of the maj. 7 all make this shape a lot more interesting than the basic 1/3/5.
Useful Triads – Major: Strings 2/3/4
These are probably the most useful major close position triads on the neck, or at least the ones I grab most frequently. I’ve been working through triads and spread triads to have a full range of them on tap as needed. Nothing fancy but worth committing to memory, particularly including the interval locations.
Pedal On 