I prefer powerlifting technique for bench press as it is much safer than using an elbows flared technique. True the elbows flared will hit the chest more, but it can also lead to pec tears and shoulder pain.
Also, for those with long arms, the powerlifting technique can still be an effective chest builder. Those with shorter arms (and hence, different leverages) may find that the powerlifting style bench press mostly hits their delts and triceps. If that's the case for you, you may want to add in some accessory chest movements.
I am long armed, so I can get a great chest workout even from the powerlifting bench press.
As for the squat, I'd stick with whatever technique suits your body and leverages. Bodybuilders tend to go more narrow feet placement and higher bar. Powerlifters tend to go wider feet placement and lower bar. But that isn't the only combination, I personally feel most comfortable with a lower bar but a closer stance.
Since poor squatting form can be so problematic, I would definitely stick to whatever style of squatting lets you hit depth pain free. Then if you have certain bodybuiling goals, choose accessory movements based off of those goals.
James 1:16-17 ESV
Do not be deceived, my beloved brothers. Every good gift and every perfect gift is from above, coming down from the Father of lights
With God's help...Mens sana in corpore sano