I've used both. Ran away from Notes the first chance I got. Outlook is what we use now at work, with Notes still performing a few legacy things.
Our Notes was installed poorly. Had I done it I would have created the infrastructure needed to allow us admins, heck even the users, to do password recovery! I spent a whole day once trying to guess the original password we gave a user that started 10 years before I arrived because they went on holiday for a week and forgot the password they set the week before.
When I go home I even stay clear of Outlook. There is only one email client I use above all others (thunderbird is second) and thats: mutt.