Get the least expensive Prius you can enjoy. There is no reason to get a low miles Prius especially after what you're about to do to your car. The only thing to be on the lookout for is your seat may get worn but with the price difference between the vehicles, $250 or so for a new seat cushion isn't a big deal.
I know I'm late to the pricing party, but I pretty much did the opposite.
I just picked up my new/used Canadian Prius Plug-in with Technology Package, which is similar to the US Plug-in with Advanced Package. It had a little over 29000 km (18000 miles) on it and was a 2012. After much, much haggling, I got it for CAD$29000 (US$23000) plus tax. It was a dealer company car. I believe they probably used it to ferry customers back and forth.
The thing looks absolutely brand new. I'm impressed. The interior is spotless and in fact, even the engine was spotless. They must have spent a fair amount of time scrubbing that clean. Came with both the summer and winter floor mats, and also two fobs. How many fobs do they usually come with? Cuz I was expecting just one.
The fake leather looks really decent actually, and I'm not even a big fan of real leather, much less fake leather.
This thing feels like a luxury car... well... except for the acceleration.

But I'm used to that, as I've owned both the 2001 Prius and the 2004 Prius. The fit and finish is excellent. However, that's because of the package, which is above the US Prius Five IIRC. I looked at a 2012 Prius v Base model, and it looked horrible, with the interior trim comparable to a cheap low end minivan of the 1990s.
BTW, licence plates here are normally blue on white but these plug-ins and EVs get
green on white licence plates. For the time being we also get HOV lane use on some of the big highways, but they're terminating that in the summer I believe. Not even EVs will get to use the HOV lanes either when they terminate this. The regular Prius never was eligible for the HOV lanes here, even when it first came out AFAIK.