I really like the DE0-CV in particular for having the 7 segment displays and accessible buttons and switches. When I was first getting started in FPGA stuff, I spent a lot of time just getting basic circuits to work, and you need some physical IO to get any feedback that your stuff works. It gives you a lot of things to learn on before you start worrying about VGA output or whatever (but does have a lot of interesting stuff on board for when you do want to mess around with that stuff!)