My favorite vocal chain right here.

• I always bring the level down to -18 based on peaks using Hornet Plugins VUmeter, so the analog compressors after it will have ample headroom, not introducing distortion (unless I want it, and sometimes I do).

• FabFilter ProQ3.
I use this to cut off the unnecessary mic lows and thumps as well as cutting out some of the low-mid room resonance that always happens, more or less. 
It’s amazing how a vocal immediately sounds way less “homebrewn” when you get the boominess 120–250 Hz out; I usually watch out for two separate peaks in that range.

• Universal Audio LA3A and LA-2 compressors. 
At some point I was experimenting with vocal comps, and just ended up having these two in a row: creates very transparent compression, and even if you squeeze the vocal really hard (7-8 dB), you literally can’t hear it. Just amazing.
Also, as a bonus, if you run the signal harder into these, the analog-modeled input stage creates this sweet distortion that can be so useful if the vocal sounds a little too tame and some vibe is required. Kind of “radio-ish” distortion.

• UAD Maag EQ: I almost exclusively use this for certain presence in high-mids. Especially if it’s a really high-quality mic, there’s always this really great “bite” in mids or upper mids, and raising the 2.5K shelf emphasizes just that.

• UAD Precision De-esser: this just works. It’s pretty simple, and I bet there are deeper and more complex de-essers out there, but I’ve found this to do a fairly decent job – just get the frequency right and then don’t go overboard with the taming.

• Oeksound soothe: saying this is a godsend in resonance work isn’t an exaggeration. There can be so much complex and harsh resonance in mids and high mids. Using this is almost like using a cheat code. Obviously you have to set it right, but then you’ll have this safety net that literally just works. I’ll tell you I don’t miss the complex nothing and EQ automation in vocal work one bit!

• Fielding DSP Reviver. 
I don’t use this one super often, but there’s definitely been times when I feel that vocal is missing a little bit of presence here and there, and getting harmonics up with this one may be just the final ticket.

• UAD Pure Plate.
I always use this for rap vocals that sound a little dry.
It’s so easy to create this subtle atmosphere that you don’t even notice until you flick it off.
If a really long, lush reverb is needed, I’ll go for something else, but for rap, this is the one for me.

All these are mainstays in my vocal bus and get the job done most of the time. I always run all vocal tracks, no matter how many, into one bus with this chain.