Upload & Sell: Off
Avoid the i1 display 2 - it is old technology and not especially reliable either. The new i1 Display Pro is far better and more consistent and more accurate and works with more monitors. They also have a new ColorMunki that is much the same but slower and somewhat cheaper. Avoid the old colorMunki that is still sold because like the i1 display 2 it does not work with the latest monitor technologies. On the other hand, it can do printer profiles and so it would not necessarily be a bad thing to have as well as an i1 display pro.
The spyder 4 might be better if you want to use it with an iPad. I think only spyder has profiling software for the iPad. Check the details for yourself if applicable.