Welcome to the Gang from Western Colorado.
If you are looking for a "new" trike, you are pretty much limited to the Tri Glide, Freewheeler or the Can Am's. Sure you could buy a new Gold Wing, have it triked and it would be "new" but depending on where you are and how local dealers view them, you could have "issues" with getting warrantee or maintenance.
In my area, I had no trouble with the local dealer (Honda) working on my 08 with the champion conversion. I have heard of folks not being able to find someone to do their maintenance.
Usually, the Honda dealers will work on the front half and trike manufactures work on the back half. I'm guessing this is pretty much true with other trike conversions as well.
Do your homework, make sure you get a reputable installer. Then be a little pro active about followups. Find out who will work on your choice and honor warrantees.
Of course, if you are able to do your own wrenching, this isn't an issue. I did much of my own wrenching all my life. Most of us have some reason for migrating to a trike ... "age appropriate" generally sums them up. In my case it was bad knees and a loss of confidence in being able to hold the big touring bikes I love up when I stop. So, if I am unsure about holding them up, probably not able to get on the ground and do the wrenching. So in my case I went looking for a "factory" trike.
After I lost that in a bankruptcy, I did get a Gold Wing and loved it. It is true that the Gold Wings are "bullet proof" (basically, but, they do require occasional maintenance more than just oil changes). Something to think about, is if you are somewhere outside your normal area, IE on a 3k mile trip and something fails on your Gold Wing, especially on the rear end, you might be in a pickle finding someone to help. Same could happen on a Harley or Can Am, but, you have a better chance finding help simply because you are riding a "factory toy".
Disclaimer: I'm not trying to dissuade anyone from getting a non factory trike, just pointing out the obvious issues that could occur.
So for me, the biggest issue to decide is "Factory Trike' vs. Conversion. Once you decide that, then do as many test rides as you can and decide which one speaks to your heart. Again, do your homework and research so you go into it with open eyes.
You're off to a good start, you will find all sorts of advice here and 99.99% of it is good (threw in the 0.01% incase I give you some bad advice in the future ... :blush
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In summary, find out what the local dealers, installers and independent motorcycle shops in your area are comfortable with and adjust your decision accordingly. The less you have to think about service and repairs, the more fun you'll have just riding ...