Choose Penpot if you're an open-source advocate or part of a privacy-conscious team. Its real-time collaboration and design elements make it great for projects where you and your team want to share design files securely and work together effectively. However, avoid it if you require a robust plugin ecosystem or prioritizing a highly polished user experience, as it doesn't match Figma in these areas.
Opt for Excalidraw when you need a casual, hand-drawn aesthetic for brainstorming or quick sketches. It's perfect for developers wanting to visualize architecture or teams needing to quickly jot down ideas in a low-pressure environment. However, if your project demands high-fidelity designs or extensive features found in full-fledged design tools, Excalidraw may not meet your expectations.