I have a huge batch of grill tools some really expensive and some really cheap ones and honestly the difference on many is negligible.
Over time i've found i dont use 2/3's of them and everytime i'm at a big box store and see those metal case grill tool gift sets, i just shake my head at the useless collection of junk.
Maybe i am alone on this but my BBQ essential tools are simple:
2 or more sets of basic locking metal tongs: one for raw one for cooked, more if you want to avoid cross contamination of different foods
2 basic metal spatulas: raw and cooked, primarily for for burgers.
If i'm using sauce i will add one silicone brush, and or a spray bottle to mop.Any BBQ brushes with bristles end up getting used as ash brushes to help clean up what ever the one touch blades dont reach on their own.
A quality instant read thermo is indespensible - a digital probe therm is very handy for indirect cooking too.
I recently grabbed a pair of silicone grilling gloves for handling butts and chickens. handy but by no means essential.
The one "tool" that never comes up but i find should be absolutely required on every cook: small white towel or better a set of them.
I find i am constantly wiping my hands,the grill,and the grilling table while grilling. Perhaps even a forehead wipe if im on the grill for a long period on a hot day. Aaron franklin uses towels to handle meat instead of utenstils to protect bark. I picked up a 20 pack at home depot for $10. They're cheap enough that you can throw out if you don't want to wash them.
As far as grill brushes to clean grates: i've had all shapes and sizes and my favorite was inside a kettle i bought on craigslist:
Its this in red:
It a no-name brand but the smaller handle makes it WAY easier to use (obviously use caution if cleaning a hot grill).
The three sided weber brushes are good for the round edges of the kettles too.