There are many Arduinos and Arduino-compatible boards out there - Seeeduino V4.2 may be one f the best. Seeeduino V4.2 is an Arduino-compatible board, based on Atmega328P MCU and it is stable, easy-to-use and even good looking.
Seeeduino V4.2 is based the Arduino UNO bootloader, and with an ATMEGA16U2 as a Uart-to-USB converter making the board operate like a FTDI chip. You can program the board via a micro-USB cable. You can also power the board via a 7V to 15V DC Jack input - simply select the supply voltage, 3.3V or 5V, via an onboard switch (useful if you want to use 3.3V to save power).
3x on-board Grove interfaces allow you to easily connect to Groves.