I like my Geissele Mk5 keymod more than my SLR solo Lite keymod. The SLR has a nice low profile and the QD swivel cup functionality is a nice touch, but they skimp on mounting hardware (no included way to torque the barrel nut and no torque specs in the install instructions for the cross bolts or barrel nut) and the keymod slots are not quite to spec on the SLR, which was very disappointing. A few keymod accessories won't fit, although most will. Also the clamping design is much better on the Geissele.
The geissele installation instructions are far clearer and more robust than the SLR's business card sized instructions. It really illustrates the difference in attention to detail between the two companies.
Next time I'll try a BCM, but so far the Geissele is the one to beat.