Is there anything special about Arduinos? I've been using the stm32f4 discovery up until now but I've heard Arduinos are easier to use. While looking for an Arduino Genuino Uno Rev3 board, I was told to get a knock off instead.

Is there any real difference between Arduino boards and other knock off micros with similar specs? 
I really just want to get a feel for what it's like using an 'easier' micro. It doesn't need to be extra special.
This is Google Trend of Arduino (blue) versus four other boards: STM32 (red), Teensy (green), MSP430 (yellow) and PIC32 (magenta).

That means lot of people using Arduino, making hardware and software, writing blogs, answering questions. That's the biggest plus of Arduino.