In the late 1970s, a method was developed to estimate acoustic intensity in one dimension by taking the cross-spectral density of two closely-spaced microphone signals. Since then, multimicrophone probes have been developed to measure three-dimensional intensity as well as energy density. Their usefulness has led to the design of various types of multimicrophone probes, the most common being the four-microphone orthogonal, the four-microphone regular tetrahedron, and the six-microphone designs. These designs generally either consist of microphones suspended in space near each other or mounted on the surface of a sphere. This work analytically compares the relative merits of each probe design in measuring acoustic intensity and investigates the various finite-sum and finite-difference processing methods used with each. The analysis is limited to probes consisting of perfect point sensors in plane wave fields. The comparison is given in terms of average and maximum errors for intensity magnitude and direction as a function of angle of incidence as well as the spread between maximum and minimum errors for intensity magnitude. After existent probe geometries are reviewed, optimization techniques are introduced to predict what the optimal probe geometry would be for any given scenario. The probe is optimized to give the lowest intensity error averaged over angle of incidence of plane waves. This is done for full-space and half-space scenarios.