Hey ! Sorry for the late reply, I was on holidays in Scotland where there was absolutely zero network. I know the jam is over but let me say thank you so much for your feedback !
For the choir VST, I have Omnia but I didn't use it this time, I used sort of a vocaloid type of plugin by Dreamtonics called Synthesizer V Studio 2 Pro if I remember correctly. They have three choir voices pack which are really nice ! It is quite pricey I'm not gonna lie (you need to buy the plugin which comes with one "free" voice but if you want other voices or choir, you have to buy it as addition... and it is not cheap) . The parameters are really easy to set up like the tremolo, the smooth notes change, the breathiness of the voices and you can separate in four different voices Soprano, Alto, Tenor and Bass that you can control individually the way you prefers. It is build like a vocaloid so it is based from real voices. You can write lyrics and it will be interpreted as sounds (most of the voices supports chinese or japanese languages but there's quite a lot that also supports english and spanish. The specific choir that I use supports chinese and english if I remember correctly). In my opinion, the plus of this plugin specifically is that I find it quite realistic for a vocaloid plugin. I use it a lot for songs demos since I'm not the skillest singer in the world lol. It gives a decent basis to work.
I like this plugin honestly, not easy to set up sometimes and it takes A LOT of ram so, if you want it, I hope you have relatively good PC components (I have a Macbook Pro M2 16gb ram , just so you know). There's a lot of downsizes compare to other plugins but, hey, the overall feeling of it makes me like it anyway.
Hope it helped ! Thanks again for your feedbacks but also for the jam, I had real fun doing it ! :D