I’ve heard great things about Youlean (above). But also, I use Logic Pro and the multimeter and loudness meter do the job just fine for $0.
I’m looking at some of the VU meters as well because they do much the same thing if dialed in correctly. There is a digital VU emulator that also has some handy monitoring switches (phase/LR flopping/MidSides/etc) but I’ve forgotten the name. Or maybe I’ll make a standard patch to hit my Nagra with the monitor signal and use the Modulo there.
I think there are many ways to do this part and whatever you start with is probably alright.
I think some of this comes down to whether the music will be listened to in a playlist or whether it will be listened to on its own/as an album. For the listener, they’ll have to mess with the volume knob every track if we’re not consistent and that won’t be much fun for them. Streaming services will automatically turn the volume up or down to match their target LUFS because they don’t want to lose listeners due to fatigue.
When we’re mastering, we usually are trying to make it sound good for the levels the listener will be receiving. If our masters sound good at our preferred level as well as a few db up and a few db down then it’s probably no big deal where we are on LUFS. But Fletcher-Munson tell us it will always sound better the louder it is and if we don’t use something (whether our intuition or a LUFS target) then we’ll be right back at loudness wars and the accompanying lower dynamic range (which is fine for some tracks of course).
It’s simpler, in my experience, to have a standard target to start with and then make decisions based on the program material, intended effect, and target delivery device. It just takes a lot of the guesswork out if I start from the same place each time.
Definitely a “your mileage will vary” thing though and I’m glad there are people advocating for an entirely intuition-based approach.