It's a matter of personal preference.
Self-guided bike tours offer flexibility and independence but maintain a level of support and convenience. Your hotels are booked, your luggage is transported, and you have maps and directions for each day's ride.
Be sure to consider your comfort level with navigating a different culture and foreign language, reading maps and signs, ordering food, and dealing with flats or other minor emergencies - some travelers don't enjoy doing these things, but others find them the best part of an adventure.
If you enjoy traveling with a group, meeting new people, and having a guide and structured daily schedule, then a guided group bike tour is probably the better fit for you.
Here's an at-a-glance comparison of the key differences:
