I am one of those humans who actively believes that her loved ones, friends included, should know how loved they are. I am constantly grateful for their presence in my life because I know I wouldn't be the same person if not for them. I will randomly text them "love you!," send along some hearts to get the message across, and end phone calls and FaceTimes with some form of "I love you." Yet, for as much as I like to tell people how much I love them, I like to tell them even more "I appreciate you."
To me, telling someone that you appreciate them is way more important than saying you love them. By actively telling someone "I appreciate you," you're declaring that you are thankful and grateful for what they've done and who they are to you. Granted, saying "I love you" can, in theory, get the same message across, but I don't think it always does. Telling someone "I love you" means that you love them for who they are, but there's no guarantee that you're grateful for their presence in your life. I love my sister, but when I'm mad at her, I am definitely not appreciating her at that moment.
Appreciate also means knowing and recognizing worth. When I tell someone that I appreciate them, I am acknowledging that they have worth to me and it is extremely high. I've told my loved ones "I appreciate you" for everything from a funny joke they've made to the advice they've given me when I desperately needed it, and anything else in between. They've managed to put up with me for this long, so I want them to know that I am aware just how much I could not do without them and how much they enrich my life.
Although love means to adore or like very much, among other definitions, and I use to love in my vocabulary quite often, appreciate has become my word of choice whenever I want someone to know truly how much they mean to me. While each use of "I appreciate you" occurs in a different conversation or in a different context, the overall thought is the same. I am so grateful for all that you've done and want you to be aware that I recognize how much worth you have. Sure, I love you, but I appreciate you even more.