BEST? How would you define BEST? User-friendly? Development time? Simulation time? Accuracy?

I have worked with these three, which are capable of doing what you described:

• TRNSYS: User-friendly, Not free, Need much more simplifications compared to real systems, reach components library, flexible HVAC loops, has no special structure for HVAC loops
• EnergyPlus: Free, takes much time to develop, lighting simulation and control, a lot of predefined standard loops, reach documentation.
• OpenStudio: Free, based Based on EnergyPlus, covers a lot of HVAC systems, the best starting point for advanced energyplus HVAC simulations