What is the best queue type for shape 30mbits + simple queue

Hi i’m having a little issue with simple queues, using pfifo with 50packts queue a subscriber with 37mbits never reaches 37mbits under full utilization, the simple queue starts to drop packets before they reach that limit. and when i set the pfifo size to 100packts, these queue gets avg traffic of up to 40mbits in the mrtg mikrotik graphs… i would like to know whats is the best queue type or setting to do a more accurate bandwitdh to my business subscribers.

thanks!