ICSE is language rich...for a child with language based learning disabilities it will be more challenging-unless of course the school is aware of the precise instructional, academic and testing accommodations.
CBSE has a higher standard for math and science....but it has one distinct advantage. It has a list of accommodations at least for testing purposes and the second language can be waived with necessary documentation. The problem though is that the syllabus as offered by the board and the curriculum as offered by publishing companies may not always allow for instructional accommodations. (The syllabus is the sequence of skills in a subject. But the curriculum is determined by different publishing houses and they create the hope that their books are for the so called 'bright.' That is a fallacy. Curriculum should be age appropriate and and allow for individual modifications for kids at either range.)
State board and matriculation syllabus may be less stressful-they are more on the age appropriate level but it depends the state-it is true that the syllabus is better in certain states as compared to others. Certain states allow for testing accommodations-it is a painful process due to lack of awareness amongst the officials and of course, red tape (as is the case with all boards) but it is not impossible.
Most challenging of all, you will have to deal with the prejudices of people around you about your child's capabilities if you select state or matriculation board. Remember, language based learning disabilities like dyslexia are not an indication of reduced potential but a clear indication that something blocks the regular avenues of learning. So spend some time to understand your own ability to cope with such attitudes and select what you think you and your child can live with.