My first printer was a Monoprice i3 clone (select V2). I eventually had an electric burning smell and shutdown issue with the printer. I opened it up and did some direct soldering to replace bad connections and adjusted the voltage (plenty of people online with this issue to help troubleshoot). Been running flawless since, but there is absolutely a problem with these machines that could lead to a fire (my reading on this would lend me to believe that if there isn't a problem with it, there will be... [if you don't want to open one up and do some soldering, then avoid Monoprice]). As many prints can fail, it's often necessary to monitor a 3D printer regardless.

I'm currently using a CR-10 as my main printer, and after some modding to the print bed, I'm very happy with how much better it performs over the Monoprice (and size advantage). The Monoprice can do great prints, but it has been way more finicky with certain detailed prints and not as great a range for printing temperatures (have to get the temp just right to succeed and seems to have greater issue switching filament brands/colors compared to CR-10). For example, the fence portion on my JD tower prototypes wouldn't come out right on the Monoprice (despite every other detail coming out great), but the CR-10 did it all as desired.