Opinions on iCloud vs. iTunes for backing up app data

As a newbie to the iPhone/Apple I'd like to know if it's better to use (or pros and cons of using) iCloud or iTunes to back up data. Have no interest in messing with music, videos, etc or pushing/distributing stuff to other devices. I just want to back up all DATA (including custom fields) associated with Contacts, Calendar (with PocketLife add-on App), Notes, Reminders and possibly other apps like Numbers and maybe a ToDo or Task list.

Just spent days manually entering 300 contacts because my old Palm Treo was too old to transfer data from. I'm terrified fo the possibity of having that data lost or corrupted by 'synching' to iTunes or iCloud. To me Synching implies merging data from 2 sources (the 4s and cloud or tunes) which could result in my contacts being overwritten, corrupted or duplicated. I just want to do a one-way save of my data to a remote storage location for backup. I'd hope to see a few generations of backups.

I'd welcome any opinions, recommendations, pros and cons of iCloud vs. iTunes. Thanks very much!