I went with the original double bypass. Primarily because I purchased it back before the single was even out.
I thought about selling it and just going with one of the newer options but liked the idea of having a dedicated port that could stay installed and I wouldn't have to worry about removing the single one if I needed to take it back to the dealer.
I decided I wanted the double bypass installed under the driver seat. Its accessible but hidden.
Mine is the original one, originally made for the Charger / Challenger... ZAutomotive makes a T type version now that puts the two OBDII ports side by side under the dash. But by the time that one came out though I had already modified the one I had to work under the driver seat.
Besides, where it is now is unlikely to be seen by a dealer tech just hopping in and connecting to the main OBDII.
These are my reasons, nothing against anyone who goes with the single or the new T type, honestly if I was buying now, I might take a different path. While the above are my thoughts on why I like it where it is at, really not sure if they are a strong enough argument should I be starting over. But I already had the cable in hand anyway.