The best systems to emulate on the Trimui Smart Pro include PlayStation 1, Nintendo 64 (with some limitations), and Dreamcast, as well as a wide range of 8-bit and 16-bit consoles like NES, SNES, and Game Boy Advance. For the best experience, it is recommended to use a custom OS like CrossMix OS. 

Recommended systems:
PlayStation 1 (PS1): Generally runs very well on the device. 
Nintendo 64 (N64): Emulation is possible but may have graphical glitches, audio issues, or performance problems depending on the game. 
Dreamcast: Playable, though performance can vary. Some games work well, while others may be slow. 
Game Boy Advance (GBA): Plays very well on the device. 
PSP: Performance is surprisingly good, though some games may have graphical issues. 
16-bit and 8-bit consoles: Systems like the SNES, NES, and Game Boy are emulated with excellent performance. 
Arcade systems: Systems like the Capcom Play System (CPS1, CPS2, CPS3) can be emulated well. 

Tips for best performance:
Install a custom OS: CrossMix OS is highly recommended for its optimized cores and features. 
Experiment with emulators: Some games have options to switch between different emulators. Pressing the "X" button on a game in the menu can show available options, so experiment to find the best performer for a specific title. 

Be aware of hardware limitations: The Trimui Smart Pro is a budget device, so emulating more demanding systems like PS2 or GameCube is not recommended. 
Consider PC streaming: The device has a Moonlight app for streaming games from your PC, which is a great way to play more demanding titles.