I've used both and both have their good points. The trekking bars have more positions and seem to have a better climbing grip. Both have ways to create numbness in my fingers on long trips. What I recently tried on a new build are
Rivendell's new Bosco Bars. They were developed to provide more positions than the trekking bar and seem to. They are the most comfortable bars I have ever used. I put them on my Hillborne which is essentially a high end hybrid and, after taking a weeklong tour on my touring bike, I intend to replace the drops on that with them also.
Marc