@Sulvek, In addition to what the others have said I'll add that 'it depends on what you want to do with your game experience.' That meaning, 'Simple Trainer' is an excellent 'base' to control the gameplay. You can do some object manipulation, but it's 'simple.' You also can control aspects of your character (be they the '3', a game ped, 'Freemode Ped' or a 3rd Party Addon Ped) by changing the 'skin' and adding attributes like increased strength, speed, and so on. But other trainers give 'more or less options' depending on which ones you chose.

All the trainers I've ever seen build upon the baseline 'Native Trainer' and give options that give more control over say 'characters and character play' or 'over map manipulation and game play.' Other than Simple Trainer, the two 'best' I've used are 'Enhanced Native Trainer' and 'Menyoo'. I also used 'Map Editor' for a short time, but it was a pain to use and though it had greater depth far as the number and type of game props than Menyoo, I ended up ditching it.

ENT gives more control over 'gameplay' as it offers many things other 'single mods' do alone. 'Flight', 'Game World Manipulation', 'Mass Ped manipulation', 'Weapons Manipulation', as well as baseline character controls plus a lot more can be found with this one trainer. However, it's weak points are skin control and map editing. It can do both about the same as 'ST', but 'Menyoo' is much, much better!

So Menyoo IMO beats out Map Editor by miles with far greater ease of use, more mod makers reference it for skins/clothing, ped animations and map props. Menyoo's greatest strengths are 'Mapmaking', 'skin control' and 'Ped Manipulation'. If you can't get a grip on 'Scene Director', then Menyoo will be your best bet to set up scenes, build sets, create characters and get peds to perform specific actions.

I currently use ST, ENT and Menyoo as each provides something the others don't. No one trainer 'does it all', but those three cover most of the bases for me at the basic level.