The biggest difference most people will see is cost, if gaming at less than 4k.
If you are gaming at 4k then I would suggest getting a TI as it is notably more powerful than the standard version. If you've got the money for one you've probably got the money for the other. In which case I suggest the TI for future proofing.
If you aren't gaming then you have to look at ROI. That said a TI is again notably more powerful in compute performance.
EDIT: I take that back the 1080 is massively cheaper than the TI, like half the price in some cases. It's a tougher argument to make to get the TI.