.io and .co are favorite among startups.
These are futuristic names. So, prepare to hold them for 2/3 years for a good return perhaps.
However, sale price is low with .io names.
If you look at VRcasino.io, it sold for only $105.
However, if you believe the name, you may want to hold it just in case a company might want to use it.
The sale price may not be a big one though considering this.
I think these are brandable names for VR products or companies, so the sales target is set to be tech startups or mature tech companies. I will probably hold the domains for years until someone purchase them.