Migrate from Tia13 to Wincc 7.5 or TIa17?

Hi, 

can I ask you which one is the best for a refactoring of a Tia 13 Wincc project?

Thanks, BR

HI

I think TIA17 appropriate for that , because after migration you will see same environment , ...

Thank you for the reply, I need it only for HMI on a PC, PLC program is not involved, so after working with Wincc7.5 I've seens that it seems a little light than TIA, and seems like the TIA  Wincc Professional, but with better tools like Tag simulation, instead of the heavy PLC Sim.

I didn't get why both TIA Wincc and Wincc 7.5 are seems to be maintained by Siemens.

Any techical reason to stay with TIA?