The Terrova doesn't have Auto Stow/Deploy, that is the Ulterra.
Depends on what options are more important to you.
Terrova - Spot-lock, can be linked to Humminbirds
Ulterra - Similar to Terrova with Auto-Deploy
I don't need stow/ deploy, I'm interested in Spot Lock, but I would want that feature to be accurate on the Lock.
I run Humminbirds.
So sounds like you could use either the Terrova or the Ultrex.
Like others have mentioned with Ultrex you have quicker response time.
I have no issues with my terrova. I fish without my shoes on and feel the buttons with my toes. I pretty much only use the remote for spotlock.
As far as one being better than the other with spotlock, I honestly.cant say because I havent used the others. However, I thought all use the same GPS technology.
With no wind, mine will bounce around some as I will drift over spot and then it recorrects.
It seems to hold better with at least a little wind.
But spotlock on my terrova certainly beats fishing without it. I cant get used to my buddies cable steer now.
So really just depends on how important the quick response time is to you.
If my trolling motor went out today, Id probably get the Ultrex, but as long as it is working Im not going to upgrade.