To guide you please answer below questions.
What's your budget?
Are you looking for a Motorized screen, Fixed screen or Manual pull down screen?
What will be your viewing distance?
How big is your room?
Which Projector you own?
90" screen will suit your room bigger than will be a overkill.
Where you are planning to place your projector? Are you going to place the projector on table or ceiling mount. With optoma placement option will be a bit tricky pl. go through the placement calculator on Optoma website.
Just make sure that walls on both sides of the screen are either dark or covered with light absorbing material else it will reflect light back on screen and make the picture on edges look washed out.
vinay - how big should be a screen for the viewing distance of 10ft?