Metal Bond Wire or Retainers After Invisalign?

As mentioned by Dr. Barnett, fixed retainers are good for patients who are not likely to follow instructions for wearing a retainer. Invisalign patients who have successfully completed treatment have demonstrated good cooperation and are used to wearing aligners that come in and out. As such, most seem not to opt for fixed wires, due to the increased difficulty of cleaning, and possibility of it coming off.
Most of our Invisalign patients opt for using removable retainers after treatment. Our protocol is to use them full-time for the first 3 months, followed by nightly wear. The retainer can be the final aligner, fabricated by a local orthodontic lab, or a Vivera retainer (ordered through Invisalign). The amount of time or type of retainer may differ depending on your particular treatment.
There are instances in which fixed retainers should be used, such as in situations where there were larger movements like extrusions, severe rotations, or severe spacing. It is best to speak to your orthodontist to determine the best option for your particular lifestyle and situation.
Good luck!

Retainers are essential throughout life. Teeth can, and often will, move as we age and our faces change and mature. Even an adult who is done "growing" can still have orthodontic changes later in life if a retainer is not worn well. It can happen even if wisdom teeth have been removed.
The only difference between the wire and the removable is the cooperation factor. With the wire, someone does not have to "remember" to put the retainer in. The wire does need to be cleaned and maintained (flossing) so cooperation is needed in terms of maintenance.
With kids, we often insist the wire be bonded to the lower front teeth and we use a removable clear aligner on the top. Kids often slack off with the amount of time they wear retainers. With adults, I give them the option. Both will work. We make new removable retainers at no cost as long as someone has been wearing them well. Of course they are expected to get old and need replaced if they are needed for a lifetime.
I would recommend you opt for the lower bonded retainer (the lower teeth have a higher relapse potential) and a removable upper retainer. A bonded retainer in the upper is prone to damage as the lower teeth bite into it.
Best of luck and enjoy your smile!