Since you'll be shooting concerts with an X-T5, I'd recommend going with the Fujifilm XF 16-55mm f/2.8 lens. Here are a few reasons why:

The fast f/2.8 constant aperture will allow you to use faster shutter speeds to freeze the action on stage, even when the lighting is dimmer. It also enables nice background blur if you want to isolate a performer.

The 16-55mm zoom range gives you good flexibility - 16mm is quite wide for capturing the whole stage, while 55mm lets you zoom in tighter on individual artists.

This lens has stellar image quality and sharpness, even when shooting wide open at f/2.8. That's crucial for keeping details looking crisp.

The optical image stabilization provides up to 5 stops of stabilization, which really helps offset camera shake when you don't want to raise the ISO too high.

For autofocus, it locks on quickly and accurately thanks to the quiet linear motors. Useful for keeping pace with a fast-moving show.

Finally, the weather resistant construction offers more protection when shooting a sweaty, smoky gig!

It's not exactly cheap, but the XF 16-55mm f/2.8 is arguably the best concert lens for Fujifilm cameras.

For concert photography with a Fujifilm camera, you'll want a fast lens with a wide aperture to handle the low light conditions. A zoom lens is also very useful to capture a range of angles and compositions without having to change lenses. Based on that, here are my top recommendations:

1. Fujinon XF 50-140mm F2.8 R LM OIS WR

• Versatile zoom range equivalent to 76-213mm
• Constant $f/2.8$ aperture throughout the zoom range
• Built-in optical image stabilization (OIS)
• Weather resistant (WR) build

2. Fujinon XF 16-55mm F2.8 R LM WR

• Standard zoom range equivalent to 24-84mm
• Constant $f/2.8$ maximum aperture
• Weather resistant construction
• Great for wider stage shots or in smaller venues

3. Fujinon XF 56mm F1.2 R

• 85mm equivalent focal length, ideal for tighter shots and portraits
• Very fast $f/1.2$ maximum aperture excels in low light
• Produces beautiful background blur and separation
• More specialized, but the speed and image quality are top notch

4. Fujinon XF 90mm F2 R LM WR

• 137mm equivalent telephoto
• $f/2$ maximum aperture
• Weather sealed
• Well suited for stage close-ups and detail shots

Those are my top picks that provide the speed, zoom versatility, and low light performance needed for concert photography with Fujifilm X series cameras. Pair any of these with a fast prime lens like the XF 35mm f/1.4 or XF 23mm f/1.4 and you'll be well equipped to capture some great shots!