Should I buy 2017 Prius or the 2018

You could wait for the 2019 Prius v says it might come as a plug in.



2019 Toyota Prius V spy shots

 

In the linked article it says:

"the vehicle is set to ditch the minivan bodystyle of the current model in favor of a crossover SUV form—a smart move considering the current craze for high-riding vehicles."

And when you ask people why they like riding higher, they always say "to see better". Yeah, meaning they can see over other cars that are not as tall. Which means blocking the view of smaller cars behind. Sort of like at a concert, you can certainly see better if you stand up, but then the person behind you has to stand up, then the person behind them.....

So eventually everyone will be driving an SUV, and when they can no longer see over other cars then everyone will start driving monster trucks.

 

Looks like no change to 2018 Prius according to the Japanese model but possible change for the interior.
20th Anniversary Edition Prius (Japan) | PriusChat

 

Does that mean there may be a US 20th anniversary one in a few years?
It does appear that the dashboard was designed to accommodate the large tablet screen. I doubt I would like it though. I much prefer physical controls.

 

I'm hoping it means that high trim models will have the 11" screen. Low trim models will have physical controls in lieu of the screen. And all models will be free of the terrible porcelain white interior.

Wishful thinking I know. Toyota can easily make 20th anniversary model in the custom order assembly line without changing the main Prius assembly line.