I used trainers/walkthroughs to play games because:
1. I don't have a lot of time to explore every bit of the game
2. Even if I have enough time, I rather play 2 games instead of 1
3. I suck at most of the games (except strategy games)
Since I use emulators, instead of trainers I rather use 'save state'. Takes less time to finally beat game as it was intended and then save your progress.
I don't have favorite trainer.