Which is the best app development services provider in California?

I’m looking for recommendations for the best app development services provider in California for an upcoming project. There are many companies offering mobile app development in the state, so I’d like to hear real experiences from people who’ve worked with an app development company in California before.

Key things I’m interested in include technical expertise, clear communication, on-time delivery, and reliable post-launch support. If you’ve partnered with a California-based team for iOS, Android, or cross-platform app development, I’d appreciate any insights or suggestions.