DSK Vst's, is a great place to check out.
http://www.dskmusic.com/
They're great!
There are like over 54 of them.
Some of them, are similar to that subtractive synth called Poisone that you mentioned.
I highly recommend them.
They are all free too!
Synth 1. Another great one.
I and many other LMMS users highly recommend it.
It's a Vst that many LMMS users can't live without.
ZynAddSubFx is another one. It's already included in LMMS.
Oatmeal, (Yes, it's called Oatmeal, Lol!
There are so many of them.
The LMMS Vst plugin wiki, made by the LMMS community etc. is also good place to check too.
https://lmms.io/wiki/index.php?title=Tested_VSTs.
Lots of options.
Well,.........Enjoy!