The best way to not step on toes here is to promote your own strengths and refrain from knocking on the weaknesses of your colleagues. You can stress to your CEO that your colleagues have strengths in XYZ areas, but the team is lacking a strong person in ABC (your area of strength), and that it would help the whole team to have someone with these skills and knowledge in a leadership role, and that is also your career goal. Make it about what you have to offer that can strengthen the team, and always compliment your colleagues strengths. Always refer to weaknesses or challenges and opportunities for growth and improvement.