Interesting question. Don’t know about amazon echo but the EV3 brick is a way of learning to program but more about concepts, high level. Raspberry pi has two variants, the zero and the normal pi. It has a huge community with a lot of examples and a lot of OS variants running on the Pi. Arduino has also a few variations. There are a few operatings systems but the rpi is really a small computer while the arduino is more a processor without all the fancy stuff (like HDMI out). I have the Arduino Mega 2560 and the rpi3 in front of me. The Arduino only has a USB slave port (for programming) and a power connector. RPI has ethernet, 4 USB ports and HDMI out, a SD card slot (running OS from SD). There is more, but mainly the OS runs on SD, you can connect a mouse and keyboard via USB and hook it up via HDMI to a monitor and you have a desktop via ethernet able to browse the internet. It is not very powerful, not like an intel desktop but still, it runs an OS with x so graphical user environment. I would choose raspberry over Arduino for these reasons. Since the raspberry is a full computer, doing something with it, like control something (home automation), you will have to learn programming and linux commands if you want to unlock the power of raspberry pi.
Which one will make a better gift for a person already owning LEGO Mindstorm EV3 and an Amazon echo; a Raspberry pi, or an Arduino?