Hardware EQ for vocal chain?

I've used the Kush, the original siemens eq and the API. I also own a LC53 by Capi but haven't used the BT50.

The Kush is very clean. I thought it was ok but I didn't keep it, I'd rather have Fabfilter for superclean stuff and the plugin version of the Electra comes pretty close, specially with very small boosts which is what you'll be doing on vocals I expect.

I like the Capi 53, I like not having too many freq options for tracking and it's more forgiving than an API550 type.
The sound is also very dependent on the opamps you use, so if like myself you find the red dots a bit hard in this eq, you can try other things for a smoother or cleaner response. It's nice on vocals, smoother than most 550 types out there which is nice on vocals and acoustic gutiar.

Out of the APIs, the PCB ones really do sound a lot better than the new reissues. For most things I wouldn't sweat it but on a vocal it's a huge difference I find, I would also go for the A over the B.

I've never heard the Iron Age but I love love love the Siemens original, I really wish I would've bought some when they were like 1000€ a pair. Now that Soundtoys came out with the plug in they are really expensive.
A little 3k or 5,6 on top on a vocal, plus a tiny bit of of the Hi band is just beautiful on a vocal, and really anything you want to open up. The mids sound great on egit, the top is amazing for acoustics. 
Definitely not the most versatile eq, it's a sweetener but it's really one of the best for broad strokes.
Try out the plug in, see if you like it, the vibe is close, the High end is quite a bit smoother on the real one but you still can see if you like what it does!

Something you haven't listed is a Pultec style eq and that's probably what I would reach for first for eqing a vocal chain because the only thing I'll usually do in the tracking phase on a vocal is add some highs, I had a Pulse tech 500 that I use for this exact purpose and it was amazing. I had to sell it at one point and now I'm using the Eq on my Tree Audio Branch for opening up the high end and it does a very nice job.

Thanks Brice and Stormy for the insight.

I tend to do too many cuts on vocals to use hardware EQ.

Fair! You're using EQ to equalize or neutralize. That's a sensible approach. Keep this up, I might like you, we might become friends. LOL

DIYRE EQP5 can be great for vocal tracking EQ.

I customized mine out with transformer and OPAMP of choice, as well as tweaked some of the EQ points (as somewhat explained on their site).
Brought the 16kHz and 30Hz farther into mid range for more of instrument eq tool than a mix bus tool. Lots of options there!

You prefer the top of the Swift to the Mäag?

If I had to have just one for the top, it would be the Swift.  But the Maag is fantastic.  It is just that the Swift is sweeter, more euphonic, whatever words work for that.  But the Maag is not harsh at all.  The Maag and the Swift actually compliment each other well.  

If you or anyone else want to demo the LH95, we have a pair of them at Access Analog powered by robots. You use their plugin to stream the audio to the analog units. A digital interface lets you change the settings on the analog gear remotely, and you can hear exactly what it sounds like.

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A pair of Great River Harrison 32EQs have been the main analog EQs in my rig for years. I fell in love with the UAD plug when I first got an Apollo and moved to the hardware shortly after. "Smooth" is exactly right. They're creamy and you can push things around like crazy without sounding off. The LPF and HPF are awesome, they've got two mid bands, low and high are switchable from shelf to bell. They're great.

Great River Harrison 500 sounds amazing. It's super flexible for anything. I love the EQ2NV, I dream about having a few racks full of their mastering MAQEQNV to create a hybrid console.