My suggestion for you in this case is to simply use the most common funcitonal for basic properties of molecules: B3LYP. I wrote in my answer here that B3LYP is still a decent functional overall, especially considering its relatively low cost for non-periodic systems (e.g. a pesticide molecule).
The first figure in that answer is directly from the paper that you said you're asking about, and it shows that overall, B3LYP is on average:
- more accurate than all LDA and GGA functionals studied,
- at least as accurate as all meta-GGAs studied,
- is in the "middle of the pack" for single-hybrid funcitonals (but is far more popular and universally implemented (it will be available no matter what software you use!)
- not as accurate as the double hybrids, but far less computationally costly!
Pesticides are extremely diverse!
There is such a vast range, for example pesticides for rodents (rodenticides) such as the organic molecule warfarin, may be very different from pesticides for algae (algicides) such as the transition-metal-containing copper (II) sulphate. We do not know a universal functional that will work well for all pesticides.
You are therefore best off in my opinion, to "keep it simple" and just use B3LYP, which is:
- not too computationally expensive,
- is more likely to be implemented in whatever software you're using, than any other functional that has the same balance of accuracy, computational cost, and popularity,
- is likely the most popular functional used for individual molecules, so there's a greater likelihood for there to be literature to which you can compare (if necessary), and more people will recognize and understand what it is that you're doing.
If you do choose to use something other than B3LYP, you're more likely to need to provide justification for why you're using it, but if you pick B3LYP, most people will agree that it's a decent "default" choice for studying basic properties of individual molecules. The Goerigk-Grimme paper to which you referred in your question, showed (for example in the second figure in my answer here) that B3LYP is quite decent for everything they tested except for reaction energies, and you are not calculating reaction energies!