There are quite a few threads that cover this - if you do a few different searches you will find a ton of info and opinions.
It really depends on what YOU want out of your trip. There are positives to riding out of each area.
What is important to you? Rentals and ride from your door lodging are available at both areas.
Restaurant/bar?
Gas easily available?
Type of terrain?
Those also factor in to people's decisions. IMO Albany is the better full service option (one stop shop for lodging, gas, food, bar, convenience store, etc.) but Centennial is closer to the top of the mountain for the hill climbing and generally steeper terrain (and the avalanche danger that goes with that - make sure you have your gear).
If the weather is bad (snowing and blowing) it is better to ride around Albany. The trees help with the visibility and it is easy to find good snow by the trails.
If this is your first trip out - I would suggest staying in Albany, riding around there for a day or two and then venturing up T trail to the top of the mountain once you have adjusted to the elevation and mountain riding.