To me, saving francesca was just a good, lighthearted read. Well yes, it does get intense with Mia's breakdown (and don't berate me for spoilers, if I recall, the first line of the book read something like "this morning my mother didn't get out of bed") but to me it just seemed very light. Not something I'd forget in a hurry but something I'd just enjoy reading, sit down in a night, go from start to finish and move on with my life, maybe revisit it a few times.
Alibrandi, however, I thought was an easy read in the fact it didn't get monotinous, but it impacted me in a much more profound way than Francesca. how many of you cried when John died? I was reading it again through second term this year during my free periods in the mezzanine noone uses in the library and I bawled from John's first mood fluctuation. To me, Alibrandi is something that stuck with me. You put the book down at the end and you sit and dwell on it. You draw out reading it over weeks and weeks because you don't want it to finish.
Even though their storylines are similar I think they're in different leagues.