Good question. I like plug-ins. Three that I started with and LOVED were TC Chorus, LexiVerb and Amp Farm. They all went bye bye around the time that Scuzzy (SCSI) stopped being a thing, if I'm not mistaken. LexiVerb was so cool cuz you could spin the graphic around and create reverse room sounds... why isn't that still a thing?? I cried when they all went away, but was happy when Amp Farm reappeared a few years ago, back on the market!
With that out of the way, Plug-ins I like and use all the time:
R-Compressor- so valuable because when I have recorded something super cool, exactly the way I like it, I dont need to add fake-digital "analog creamy texture to it", often I just want to compress something and NOT change the sound-character at all. R-Comp does it perfectly.
UAD stuff: API 560 graphic EQ, EMT 140 Plate Reverb, Distressor (great emulation, and sorry... better sounding to my ears that the Empirical Labs Arouser) All the different UAD LA-2A, so musical and YES it adds creamy analog warmth to vocals that I didn't record haha! (speaking as a mixer of other people tracks).
I love SoundToys Decapitator, EchoBoy and PhaseMistress
I love Waves MondoMod for ultra intense tremelo effects
* others: Blue Cat Chorus, Valhalla Shimmer, Vahalla Plate
*plug in instruments: Oddity (Arp Odyssey emulation) Arturia MiniMoog thing,
The three old IK Multimedia sets--Miroslav Philharmonik (an orchestra recorded on tape, apparently), SampleTank and SonikSynth
Lets start with those!
I see those super young producer working with FL Studio, and there are tons of plug in sets for that which represent a new way to work, and I think the results are amazing. I would like to learn that set of tool at some point. I have added things to my arsenal as I go along, but also remember sounds that I like from every era of studio equipment.