Depending on what you were skiing, there are likely safer options, but there's really no safest.
You're looking for something with consistent release parameters that are not to much for your
ankles to handle. I've been on Radar RS-1's for a couple of seasons now, so my preference is
for a boot that you can reference the release on dry land.

I'd look at the Fluid Motion E-Series and the Obrien Elite (should be ready by the spring).
In addition to those two I'd consider the Radar Strada, to a lesser extent the Obrien Prodigy.
D3 has a new boot called the T-Factor. Supposedly it's got some clever trick to it that lets
it release much easier than similar front lace boots like HO Approaches or Connelly Enzos.

With the RS-1s, my ritual has come to include rocking my heel up and down. This is in part to mentally settle in, it is also in part to make sure the cuff opens the way I'm expecting it to: kind of a mini release test.

Anyway, the E-series and Prodigy will probably be the best candidates. They use the same step out release, but they use a breakaway cuff instead of the expanding collar. Once you know how tight the friction nut on the cuff needs to be, you should pretty much be able to set it and forget it. Because there is not much upward movement, except when crashing, the cuff doesn't need to be very tight.

With that bad an injury, I would suggest having a conversation with Paul Jager.  Jagersport.com.  He has many options and would help you find what will best protect and support your ankle.  To each his own; but, I have had great performance with the FM hardshell front for years.  Has never prereleased and has released when it should 100% of the time.   Paul has always bent over backwards to answer all of my many questions.  No, I have no interest whatsoever in his company.  Just want to share my positive experience in hopes that it will help you out.  David McLeod