honestly what is the best portrait lens for a canon 90d that wont drive me insane? im so fed up with my 50mm f/1.8 because even though everyone says its the holy grail for beginners the autofocus is just missing half the time and the bokeh looks kinda jittery or nervous if that makes sense. im trying to take some nice shots for my sisters engagement party next month here in rainy seattle and the lighting is going to be trash so i need something that can actually handle it without hunting for five minutes.

ive been looking at maybe a sigma 18-35mm but idk if thats long enough for portraits or maybe the 85mm canon but then with the crop factor i feel like i have to stand in the next county just to get a headshot. my budget is around $700ish maybe a bit more if i can find a good deal on ebay. i just want that creamy background look without the frustration of blurry eyes every single time i press the shutter.

should i stick with primes or is there a zoom that actually works for this? its just so annoying spending all this money on a 90d body only to have the images look like they came off a phone because the lens is struggling. seriously i just need something reliable...