Personally, I only use 3 modes:
1. STRAIGHT (no DSP, use this for Discrete sounds like Dolby Atmos and DTSX)
2. DTS NeuralX (use this 99.9% of the time I am not using STRAIGHT mode)
3. DSU (Dolby Surround Upmix) - I use this probably 0.1% of the time I am not using STRAIGHT mode
I would not use any other DSP modes because they sound like a joke to me.