The main motivation for this work was to analyze the effects of basis sets on correlated energies. To this end, MP2 interaction energies of 20 complexes belonging to the S22 test set were computed, in the most common Gaussian-type correlation-consistent bases as well as in plane waves, for which we implemented the MP2 method in the CPMD planewave pseudopotential package. Although more computationally demanding at such system scales, plane wave calculations have been made accessible on conventional computing architectures through an extrapolation protocol involving both the virtual space orbitals and the supercell volume, ultimately requiring no more than a few days per molecule on several high memory compute nodes. By comparing atom-centered interaction energies with plane wave results, we established that both basis set types provide consistent values, especially when the counterpoise (CP) correction eliminates the BSSE from the former. Indeed, (aug-)cc-pVXZ relative energies generally converge towards plane wave values, free of BSSE, for progressive enlargements of X=D,T,Q,5, and differ by less than 1 kcal/mol for X ≥ T. However, the slower convergence of the cc-pVXZ bases makes their agreement with plane waves occasionally better with only half of the CP correction due to a fortuitous error cancellation between the BSSE and their basis set incomplete-ness error (BSIE). Overall, the aug-cc-pV5Z basis set with the CP correction provides the closest interaction energies within 0.16 kcal/mol to the fully converged plane wave results. This demonstrates the benefits of diffuse functions in the description of long-range interactions as occurring in weakly bound systems, although their faster energy convergence may slow down for stronger (covalent) interactions .