As of my last knowledge update in September 2020, I can't provide real-time information on the "best" SMM (Social Media Marketing) panels in Bangladesh, as the popularity and reputation of these panels can change over time. To find the best SMM panel in Bangladesh, you can consider the following steps:

1. Research: Start by doing a web search and looking for reviews and recommendations from other users. Look for panels that are known for reliability, quality of service, and customer support.
2. Ask for Recommendations: If you have connections in the social media or digital marketing industry in Bangladesh, ask for recommendations from them. They might have personal experiences with specific panels.
3. Check Online Communities: Forums and social media groups related to digital marketing and social media management often have discussions about SMM panels. Participate in these communities to get insights from experienced professionals.
4. Trial and Error: Many SMM panels offer trial periods or low-cost packages. You can try a few different panels to see which one works best for your specific needs.
5. Customer Support: Reach out to the customer support of the SMM panels you are considering. Evaluate their response time and willingness to answer your questions.
6. Pricing and Services: Compare the pricing and the range of services offered by different SMM panels. Look for transparency in pricing and understand what you're getting for your money.
7. Security and Privacy: Ensure that the panel you choose follows best practices for security and privacy, especially if you'll be handling sensitive client information.
8. User Reviews: Check for recent user reviews and testimonials for SMM panels in Bangladesh. This can give you insights into the current quality of their services.
9. Customer Feedback: If possible, get feedback from other professionals or agencies in your industry who have used SMM panels in Bangladesh.
10. Legal Compliance: Ensure that the panel complies with legal and ethical standards in terms of social media promotion and advertising.

Please note that the SMM industry is subject to constant change and the popularity of specific panels may rise or fall. Be vigilant in your research and consider your specific needs and budget when choosing an SMM panel.