Costa Rica is farther along the “progress” scale than Ecuador, especially along the coast. Coastal Ecuador lacks infrastructure, to be honest. Municipal water and waste treatment facilities just don’t exist in many places. For this reason, you’ll find under-developed stretches of coast. Pretty beaches where you’ll be the only one there. No high rises or big resorts. Inadequate health care, too. Costa Rica, of course, is much farther along in this “path of progress.”
As for culture, you’ll find theater, orchestra and mega concerts take place in the major cities of both countries (San Jose in Costa Rica and Quito, Guayaquil and Cuenca in Ecuador). In smaller towns, you’ll have local cultural events.
I will say that Ecuador has very good roads, and Costa Rica’s have improved vastly in recent years. When it comes to beautiful beaches, Costa Rica wins. When it comes to gorgeous mountains, you won’t find anything better than Ecuador’s Andes.
Truly, what it comes down to is your personal reaction. And I personally would suggest you not try to focus on a country but that you, instead, sharpen your focus to the particular community that works best for you. The community (and how it speaks to you) is what it’s really all about.