Cant decide between Mass effect or this. I really just want to know that it doesnt fall into the usual trap of ubisoft repetitive with the "towers" and unlocking parts of the map.
Almost every open world game has Towers aka side activities that are just there for the sake of increasing play time. Horizon may also have something like that, but they don't suddenly make the game bad.
If you have to choose between the two, then i'd suggest waiting until both of them are out, so you can have better idea of what you are paying for.