★★★★★ UNI Training (Vieux Port) is a small boutique gym near the Basilica Notre-Dame -- super convenient for those who live in the area, or a perfect holiday gym for fitness nuts who don't want to miss a workout.
As a boutique gym, UNI training puts more emphasis on personal training and classes, and it seems that pretty much everyone that works here is knowledgeable on some aspect of fitness. They definitely strive for quality here. E.g., although the gym is small, it's thoughtfully designed in terms of equipment+placement, and there's almost everything any fitness enthusiast would want. They even have a platform for DLs/OLY, and you don't have to worry about making too much noise since it's located in the basement.
For those interested in the personal training aspect -- I've been training with Curt Griffin for powerlifting, and he's been extremely helpful. However, from what I've observed, he has clients of all different personalities and fitness goals, and deals with all of them like an absolute pro. He will listen to what you want and your concerns, and adapt your training to suit your goals and style.
Overall, the vibe here is pretty low-key and no-frills, which I love! It's generally understood that everyone that frequents the gym is there to exercise and better themselves, and I feel the atmosphere to be quite comfortable and judgement free as a result.
Finally, this gym has the strongest air-conditioning of all gyms I have ever been too. It's amazing.