What should I look for when buying a Docker motorcycle

I’ve been interested in motorcycles for about a year now (I’ve gotten my license and everything). I’ve been riding my friend's bike but I’m finally ready to buy my own. I’ve been doing my research and I feel like I want to settle on a docker motorcycle but I’ve been hearing mixed things about it from people.

I need something that is super reliable and does not require constant maintenance. From what I’ve gathered Docker seems to be one of those brands that is either loved or hated, no in-between. Some people swear by them and others swear that it will leave you stranded, online reviews are also all over the place and aren't helping. I’ve been considering buying second hand or refurbished or just ordering straight from Alibaba.

What I am specifically interested in knowing are:

Are there certain model heals or engine sizes to avoid? Is there any specific thing to test ride that might not be obvious How are parts in terms of availability for repairs

I know the usual advice is to buy Japanese but those are way out of my price range and Docker might be the middle ground I am looking for. I would really appreciate any input and advice on this.