Acrylic can be polished, depending on how bad it is. There are polishing compounds for it. Do an internet search. It does take a fair amount of labor to polish it.
If you replace it, any material from a reputable manufacturer should be fine. I have a 15-year old acrylic shower pan that is used daily and looks absolutely like it did new. It was not cheap. I got what I paid for.
Don't abuse it, clean it regularly and use only the cleaning method recommended by the manufacturer.