Medaly: My husband is from the Canary Islands and I am from Argentina. If I were to say te amo to my husband, rather than taking me seriously he would think I have turned "telenovela" on him. I would probably end up laughing on the floor if he were to say something like that to me.
Te quiero is the most common way to express romantic love (and human affection in general) in the real world. Te amo belongs to the world of telenovelas and romance novels.
I am sure that other native speakers will coincide with me on that one.
Lissah3: But my husband from Venezuela always said te amo to me. Do you think that means maybe he never meant it?
Medaly: Well, he probably does mean it. Still it is not that common to use it outside of telenovelas and boleros.
Marijosé: Te quiero and te amo mean the same but are used in different contexts. Te quiero is used regarding love but in any context: family, friends and one's partner. Te amo and anything related to the verb amar is used only when you speak about true and romantic love. Therefore is not so common to hear it, and it is frequently used in novels, poetry and soaps.
Mulmex: Estoy de acuerdo con Marijosé.
Words can have more than one meaning. Esperar for example can mean to wait, to hope or to expect. Querer has two uses: to love, and to want. As Marijosé pointed out, amar is usually a bit stronger. I don't agree that it is always romantic. In México it is commonly used with mothers, and grandmothers as well as with lovers and husbands. Te quiero can also be used the same way. However, you would never say te amo to your best friend, but te quiero would be fine in that case. Me encantas can also be translated as "I love you," but is rarely used as such. Me encantas is more commonly used for "I'm enchanted" (by you). I believe usage varies by country and region to some extent. It can also be a question of habit. Through time, a particular couple may just choose te quiero over te amo or vice versa. Whatever makes you happy.
Saying "I want you" is a little bit different. Te deseo can mean I want you as in to desire someone. You would not use te quiero to say this. When you want someone to do something you can't say Te quiero tirar la basura for I want you to take out the trash. Instead you would say, Quiero que tires la basura, literally I want that you do something.
None of this is cast in stone. These are just my observations. Feel free to disagree.