Now, i have to admit i Amore both series! I'd say harry potter is unisex and appropriate for all ages, whilst twilight adresses mainly to teenage girls. HP talks about friendship and love, while twilight is più romantic! Also, hp gives lessons of life, although maybe in some cases, i would prefer Leggere twilight.
Finally, They are both written da two very talented and imaginative writers, j.k rowling and stephenie meyer. They wrote these libri to give teens (and not only) inspiration and time of happiness. So, if te don't like one of these two series, don't blame them! We can't all have the same tastes!
