12vdc 80w PWM transistor?

hi there i am making a project and i need to control the speed of motor with my arduino and the motor is of 12vdc and 80w can anyone recommend me a good transistor that can handle this much current ?
i have tried google but there are so many options that i am confused

What is the motor? If you really mean 12V/80W then that is less than 7A. If you only need to control speed and not direction then you just want an N-channel logic-level MOSFET and there are many that can handle that sort of current. I've used STP36NF06L and FDB7030BL which are both reasonably priced but there are loads of other possibilities. I'd look for at least 30V and 30A because you want some headroom.

Steve

motor is a diaphragm pump and i think it doesn't need more than 7A to start (starting current) am i right ?

Starting/stall current is usually many times higher than rated current. Measure the resistance between the terminals
to calculate starting current. I = V/R

I'd suggest using a suitable low-resistance MOSFET (depends on the stall current what's suitable)
driven from a MOSFET gate driver chip such as MIC4422 (many many are available, you just need a
low-side driver).