What Are Your Most Popular Dev Kits or Reference Design Kits?

I've enjoyed the kits labeled "Inventor kits" and "engineering kits". Sensor kits are cool too.  

Personally, I'm a big fan of any boards that use the standard layouts such as Arduino Uno or Adafruit Feather.  As such, the Nucleo boards from STMicro are always great to work with since they are Arduino Uno header compatible and usually have decent examples to work with.  Same is to be said about the boards from Nordic Semiconductor

Arduino Uno and Raspberry Pi is my favorite.

STM32 Nucleos are very popular. I have seen them everywhere where the serious MCUs designs are made.

I think that there are two key things for making board popular:

1. Price to performance ratio
2. Brand

At home for years I have always had an Arduino UNO on the table for any proof of concept or to teach something to my children. At work I usually work against sales terminals and pin pads of all types and the development environments are usually proprietary.

By the way, as a Newark employe you can ask your colegues form store department for listing best sellers...  Maybe it is more interesting than we think.

I tend to like development kits that relate to parts that I might want to use in my current or future designs.  The kits that I have gotten the greatest value from were some of the Atmel (now MicroChip) 'Xplained' boards/kits. I used a few of these boards to prototype some of the products that I have produced.  They assess to each pin on the processor and allow you an easy way to interfaces chips to the processor.

I have purchased several of these boards, utilizing different processors from the ATtiny and Atmega families.

Arduino UNO

After attending path to Programmable 3, its Ultra96

Xplained boards are nice, but newer Curiosity Nanos are better, I think.

I quite like the Atmel Xplained evaluation kits. This was perhaps influenced somewhat by the educational content that Atmel ran alongside them.