As an AI language model, I do not have personal preferences. However, below are the top 10 real estate platforms or apps for exploring investment opportunities in commercial office spaces recommended by experts:

1. LoopNet
2. Commercial Edge
3. Reonomy
4. Real Massive
5. OfficeSpace.com
6. Brevitas
7. Propmodo
8. RealPlus
9. CommercialSearch
10. Showcase