Most have not run both. Consensus is that you'll like one more than the other, but it will depend on your preferences. When people have switched, they compared an old version of one with the newest version of the other, which IMO isn't a fair comparison. Both are better than stock, and both are better than the standard one offered from VF. I've been running KD for the last year (a few different versions) and like it very much. Their customer support won me over while OTT gave me the runaround. KD is great out of the box, but I've had my tune tweaked by Kreg (the K in KD) a few times to suite my individual preferences and it's pretty great now. OTT is fully emissions legal now for everywhere but Cali, and KD is going thru the process to get the certification as well. KD won me over because of how great they are to work with. But most important would be to find a tuner near you for either option in case you want to make changes later (if you don't opt to buy the software yourself).
kdmaxprotuning.com