Buy the Bosch HMD8451UC 800 24" Stainless Steel Microwave Drawer.

This is an appliance you install into your counter and live with for a decade, not a gadget you can swap out when it starts arcing.

What was compared

1. No reports of the Cosmo's arcing fault
Cosmo owners describe the microwave arcing inside itself after just 9 months, a genuine electrical hazard in something you use daily near food. Nothing in the Bosch feedback, including owners nearly 4 years in, mentions arcing at all.
2. Problems start at year 4, not day 1
Cosmo buyers report clunking sounds and failing control panels straight out of the box. One long-term Bosch owner is still reviewing theirs after almost four years of normal use, which is the gap that actually matters here.
3. A built-in you can trust to outlast the warranty
Bosch has decades building appliances meant to live inside cabinetry for years. Cosmo's manufacturing is outsourced and its own research notes mixed quality control, which lines up with the arcing and panel complaints from owners.
4. Reheats right without you guessing power levels
Bosch's automatic sensor programs read the food and set time and power for you, something you will actually use every single reheat. Cosmo only automates four presets, melt, soften, popcorn, beverage, leaving everything else to manual power-level guesswork.
5. Yes it costs $200 more. Buy it anyway.
The Cosmo saves you $200 up front, real money, no argument. But that saving evaporates the moment it arcs inside year one and you are relying on an outsourced brand's support, while the Bosch is the one still working after four years.