I just recently had to make the same decision between a Powerdrive and a Terrova because I wanted a unit with autopilot. Even though it is more expensive I chose the Terrova for the following reasons.
1) The steering is faster than the Powerdrive, at least the analog Powerdrives. I have never run the digital V2 Powerdrive so I have no comparison. My old TM was cable steer and the Powerdrive was way to slow for me.
2) I liked the foot control much better. Again, coming from a cable steer, I was used to the heel/tow foot pedal and the very low profile and reduced foot motion was a big factor. In addition, it also has the toe operated buttons similar to the Powerdrive but more ergonomic. The downside is that it has a bigger footprint than the Powerdrive unit if that is a big factor.
3) The speed control is a dial rather than the slide control of the Powerdrive. To me, the slide control was very hard to operate accurately with my foot while the dial is a snap and there is enough rotation that it is not supersensitive.
4) The stow/deploy system is much better than the Powerdrive even if you're not old like me.

Another plus is that when stowed the power is shut off so that you don't accidentally turn the prop on in the stowed position and when you deploy it again, it's at the same setting you left it.
I did not get the Universal Sonar model mainly because it was no compatible with my fish-finder unit. I am generally against multi-functional units anyway because if one of the functions fails, it not easily replaced.
The Terrova does not have a full thrust Burst feature but full thrust is available just as quickly by use of the speed dial.
I bought the 12V model because of lack of battery space for 24V which would have also required a full rewire. But in my opinion, there is no such thing as too much trolling motor power so get as much as you can afford. One of my fishing partners has a 24V Powerdrive on an 18' boat with a fairly low profile and wind and waves occasionally give him a battle for boat control.