The difference between a really good blender and an ok blender are:
- the consistency-smoother and thicker drink
- less chunky bits that you either leave at the bottom of the glass or almost choke on when drinking
- endless amounts of things you can make, soups, nut milks, nut butters...
- blender burn out-having to replace every couple of years
When you have a good blender this will make the difference when adding greens as it will fully break them apart and provide a smoother taste (which turns a yucky spinach smoothie into a strong and healthy Hulk smoothie for the kids!)
I have and love the Vitamix but understand that you might not want to make that kind of financial commitment. Prior to the Vitamix, I always loved my Cuisinart blender and it held up really well. The Nutribullet is an affordable option which does a great job for blending heartier ingredients and also has a nice 1 serving option. These are not required if you already have a blender, but if you are interested in a new one, these are my 3 favorites.
Let me know what your favorite blender is and feel free to ask me any smoothie/blender questions you might have.