So my recent foray into concert photography yielded some interesting observations, primarily that aperture is everything if you're in low light and don't want to crank ISO, and you can deal with shallow DoF.

My go-to lens has been the 24-120 f/4, and it's a fine fine lens, but man I hate noise and am wondering if I might benefit from the extra full stop of the 24-70 f/2.8.

I found that I rarely needed the extra reach of the 120; with my backstage access if I did need to get closer, well, then I just stepped closer!

Considerations:  
-Focus speed and accuracy.  How's the 24-70 compare the the 24-120?  I find the 24-120 focuses as fast as I need.

-Aberration/Distortion.  The 24-120 does a pretty good job of minimizing aberration and distortion (at least to my eye), and the correction filters built into LR solve whatever problem might develop.  How's the 24-70 on this subject?

-Cost.  The 24-120 is paid for.  It's a sunk cost, and essentially free at this point.

-Usability:  The 24-120 ain't a feather, but it's not too cumbersome once you get used to it (25 oz.).  The 24-120 is about 5.5" at 120 mm, and about 4" at 24mm.  The 24-70 seems to be about 32 oz.  Length is a hair longer, but change in barrel length across focal length is smaller.

Cost looks to be about twice what I have in the 24-120.

For those of you that have both, what's your opinion?

Is this on full frame or a crop sensor camera? I shot a lot of concert stuff with an 18-50/2.8 on a crop sensor, the 24-70 would be similar on a full-frame. I needed the wide angle a lot, but depending on exactly how you're shooting things you might not get use out of that.

Dark environments I wouldn't go smaller than 2.8 if I could help it, fast aperture just makes everything easier. A 35/1.8 and/or 50/1.8 might be a relatively low cost experiment for you also.

I really like the extra reach of the 120 vs 70, and that wins me over.  My Nikon 24-120 is my go-to lens for most things.  Except indoors.   For that, my 85 f/1.8 and 35 f/1.4 are the better tools.

The 24-70 f/2.8 is such a ubiquitous lens, though, you probably couldn't go wrong.  I've had older equivalent lenses, but I can't say how this latest one is.

I have both options for my Canon cameras.  I use the 24-70 F2.8 almost exclusively.  It is a MUCH better lens than the 24-105.  But with that being said, I'm a bokeh whore so I want that blur for background separation and F4 just doesn't cut it for me.

Yes, crop sensor.  D500.

I've got a 35/1.8, never even thought about that one.  Also have a 50/2.8 Macro, that thing is amazing for non-macro as well.

My typical light load is the 24-120, a 70-300, and the Tokina 11/16.

I found I rarely needed the 70-300, and the Tokina got used rarely (I have come to really like GoPro for super wise angle stills).  But it sucks in low light.

Kendall Street Company by FredMan, on Flickr

You can't go wrong with a 2.8 24-70.

Canon has a really nice 28-70 f/2 in their RF mount.

And is about to have an RF24-105 f/2.8 with internal zoom.

They’re expensive though.

I think Fro used the RF 28-70 f/2 for his concert photography with Poison a couple years back.

See, that’s what I’m thinking.

And then I’ll want the 70-200 AND the 14-24. With my existing 200-500, I’ll have all my bases covered and can ditch all these, except the 105 macro.

Pelican 1604 by FredMan, on Flickr

Sounds like a plan to me. I have the EF 16-35, 24-70, and 70-200. All in F2.8. I also have a Sigma 50mm F1.4 art lens. I don't do anything which requires a longer lens. Most often, I have the 16-35 on there, but the 24-70 sees a lot of action too. Outdoors, I rarely have anything but the 70-200 on unless I know I'm going to be doing close up work like at a car show etc.

The very best 2 lens kit is a 24-70 f/2.8 and a 70-20 f/2.8. You can capture 99% of everything you want with this combo.

While I agree, there are some fantastic prime portrait lenses out there.

I did the senior photos for my daughter last year. I rented the Canon RF 85 f/1.2 for my R6, which was absolutely gorgeous. I also rented the RF 24-70 f/2.8. And while it did look very good, It couldn’t hold a candle to that f/1.2 85mm. I also used a Soviet built Helios M44-2 58mm f/2 which has some very unique swirly bokeh and looked amazing as well.

Once you get a couple of good solid f/2.8 zooms, you’ll want to start looking to branch out for more unique artistic looks.

There is no replacement for prime lenses. That is something that can not be argued. If all I was ever going to do was shoot portraits I would probably only need one lens and that would be my Nikon 85mm F1.4D. That is hands down my very best portrait lens I can think of. Add in the dynamics of a wedding and you should grab a second body and toss on the 70-200 2.8. I love my prime lenses but if I was to be limited to 2 lenses it would still be a 24-70 2.8 and a 70-200 2.8