this is a pretty vague request
what do you already use and why do you feel it's not enough?
I just use the things that come with fl studio, as simple as that. But i sometimes feel limited by what they have to offer.
fl studio comes with a ridiculous amount of incredibly powerful tools - waveshaper, gross beat, love philter, effector, convolver, directwave, edison, harmor, sytrus, sakura, etc
and on top of that there's flowstone where you can design your own synths & fx from scratch
if you really know how to use what is already available in fl there is very little you can't do
the records that inspire you were likely made with way, way more limited sets of tools
getting a pile of fancy software you don't know what to do with instead of mastering what you already have is the main pitfall of working itb
and it
will set you back in the long run