Finding the best professional logo design service depends on your specific needs and preferences. Here are some popular and reputable platforms where you can find professional logo design services:

1. **99designs**: 99designs is a well-established platform that connects businesses with professional designers. You can run design contests or work one-on-one with a designer.

2. **Designhill**: Designhill offers a range of design services, including logo design. You can create design contests or hire a designer directly.

3. **Crowdspring**: Crowdspring is a design crowdsourcing platform that allows you to start design projects and receive proposals from a community of designers.

4. **Looka (formerly Logojoy)**: Looka uses AI to generate logo concepts, which you can customize to create your professional logo design.

5. **Tailor Brands**: Tailor Brands offers logo design services powered by AI. You can input your brand information and preferences, and it will generate logo concepts for you to customize.

6. **Penji**: Penji offers unlimited graphic design services, including logo design, for a monthly fee. It’s suitable for businesses with ongoing design needs.

7. **Upwork**: Upwork is a freelance platform where you can find experienced freelance logo designers by browsing profiles and reviewing portfolios.

8. **Fiverr**: Fiverr is another freelance marketplace with a wide range of logo designers. You can explore designers’ profiles, read reviews, and hire someone who matches your criteria.

When searching for the best professional logo design service, consider your budget, the level of customization you need, and the specific style or concept you want for your logo. Review portfolios, read client reviews, and communicate with designers to ensure they align with your project’s goals.