I am sure that most of the children books Authors have this question in their minds and there is no definite answer to it. I have illustrated more than 200 books now, and also worked for various publishers/self publishers across the world and I have found that it really does not matter.
If you are willing to do the hard work and promote your book , then self publishing can give you very good results. You can make use of E-books / E-book publishing , where the world can find your book at one click and platforms like the Kindle give you an abundance of opportunities.
After you finish writing, if you decide to take the publishing route, then you must start your marketing effort as soon as possible, get a website for the book title, promote it among your friends, relatives, schools, libraries, community meetings and every other place which comes to your mind. You can also make you if the digital marketing, which can promote your book on Google and other social media platforms.
If your planning is good and you are clear about the budget which you have for marketing, then you can take help from online consultants, for you book promotion online. Self publishing will never give you any guarantee of book sales, although they will give you the access to routine book distribution channels, but no guarantee of physical distribution. The self publishers basically make your book print ready and nothing else. They may offer various packages which will include showcasing your book at various international book fairs, but please don’t get fooled . None of the self publisher will take guarantee of selling your book . So, always choose a publishing package which does not cost you more than $600 and the rest of the things can be done by yourself.
If you allow the self publisher to take care of your book marketing, then be rest assured that you are wasting your time and energy, so take charge and make your own marketing strategy which is more cost effective as well as time effective.
There are companies like the blueberry illustrations which can publish your book in $599 and provide you various channels of distribution along with the ISBN number.
So, keep searching and try to keep your self publishing cost as low as possible and try and speak to some famous children book authors who self published and got success. Making own plans for marketing will always give you better results.