Either or would be fine.
Words themselves can be very powerful. Choosing the right words for you to get your point across, knowing what they mean to you, and using them in a spell is more important than memorizing them. Sometimes, you will memorize them through the ritual being repeated over and over again. It's a lot like actors memorizing their lines through practicing the blocking.
It's whatever makes you comfortable. Stumbling to remember the words could be a distraction. Just make sure whatever you are reading off of is comfortable and stable.