I'd say there's no single and clear-cut answer to this question. Arabic has a somewhat more complicated writing system, difficult pronunciation (for most people), larger vocabulary, inconsistent plurals, a (rather simple) case system in MSA, and multiple dialects. Hebrew verb conjugations are more complex IMO due to issues with guttural consonants, strong/weak consonants etc. which don't exist (the issues, that is) in Arabic, at least not in MSA.
My language pages: http://babelfish.50webs.com/
מן המקום בו אנו צודקים לא יפרחו לעולם פרחים באביב (יהודה עמיחי)
From the place where we are in the right, flowers will never grow in the spring (Yhuda Amihay)