Cherry MX Red and Outemu Red are both linear switches with short pre-travel and a smooth actuation feel throughout the entire keystroke. Both are well-suited for typing or gaming, but the Cherry switches are generally more durable and consistent in switch-to-switch performance. That said, the Outemu Red switches have a clear housing, making them a good pick if you'd like to prioritize RGB lighting.
Outemu Red and Gateron G Pro Red switches are extremely similar linear switches with smooth actuation all the way through the keypress and short pre-travel. Both switches are well-suited for typing or gaming. The Gateron switches are a bit lighter, but this difference isn't significant, and most people likely won't feel the difference.