Repair stripped aluminum hole

Last week I had a motor mount snap in the aluminum.  While replacing the mount, I discovered that one (of the 2, hence broken aluminum) had been completely stripped out and the bolt was just placed in the hole.  I suspect the shop that did my timing belt 14k ago, but cannot prove it.

The bolt in question goes into an aluminum bracket mounted to the front end of the motor.  Car in question is a 2012 TDI Sportwagen.  Bolt is a M12 1.50, but also has toasted threads at the end.  I am not married to this bolt.

What does the hive feel is the best solution to fix this hole?  I am looking at a threadsert, is there anything better?

Buy a M12x1.5 helicoil kit and be done with it

So long as you aren't using a helicoil, I think that's a good path. 

Personally I like key-locking inserts like this  https://www.mcmaster.com/threaded-inserts/18-8-stainless-steel-key-locking-inserts/

I'd do the heli-coil as the first option. Requires the least amount of stock removal and is easiest.

Is it possible to rethread the hole for the next size up bolt and use a bigger bolt?  How about a thru bolt with a lock nut on the back side?

Try to find a Time Zert helicoil, stronger than the other type.  Try NAPA or Auto Zone to rent a kit.These are what's in the kit you buy for repairing stripped out spark plug holes.  However! If you happen to have a stripped out spark plug hole, tried to repair it and screwed THAT up, I have a kit of Time Zert oversized helicoils.  A $450 kit for one frikkin' hole. 

Never use Helicoil brand. Use Timesert or KeenSert.  They are a solid piece, not a coil of square wire.

There is nothing wrong with Heli-Coils. They are often specified in the manufacture of new aluminum/magnesium aircraft/aerospace components as well as repair of the same. Heli-Coil are actually very close tolerance diamond shaped wire with radii on each corner of the diamond. They come in various alloys with hardened stainless steel being the most common. They are easy to install with the least amount of stock removal from the part. Have used various locking and non-locking inserts but Heli-Coil is always my first choice unless original tapped hole is way oversized or totally destroyed. 

I use time-serts for spark plug thread repairs,

All others get helicoils, and I have used a metric crap load of them working on old Harleys.

I have one tool box drawer that is stuffed with helicoil kits of nearly every size...

A helicoil insert will increase the holding power of the fastener by 3+(5?) times due to the increased grip area.

I'll add that I have never had a properly installed helicoil fail.

Helicoils back out because there is no locking mechanism.

They're a spring, so with heat cycles and vibration they work themselves loose.

I've seen both of these failure modes.  For a random hole, sure, but for a motor mount where failure means the other bolt pulling out and stripping I'd go with something more reliable than a helicoil.