Who writes quality, reliable, fast themes that are well maintained?

[Stephen-FFC]

I've just has a bad experience with a theme that hasn't survived Prestashop's update from 1.7.7.0 to 1.7.7.1. It was written by quite a prolific coder on Envato Market, however, it was included in my Elements subscription, so it might be one of his "throw-away" themes that doesn't get much love. Whatever the case, I am now scared to use more by him.

Can I get recommendations of theme creators who write good code?

Issues that I value are:

• Clean, quick loading code that won't slow down my whole site that's not buggy or rushed.
• Integrates well with other people's modules (Conforms to the right standards)
• Puts out updates to themes when they are needed
• Communicates with customers (Not necessarily full support, just a quick answer here or there)
• Provides good backend customisation tools so I don't have hand code the theme's CSS files to just change the colour of the buttons throughout the site.

I know this seems like the requirements for all themes and what every coder claims to deliver, but reality based on personal experience is different. For now, the perfect theme is not necessarily the most beautiful one - it's the one that has the site running effortlessly and won't keep me up at night.