– There is a greater range of limits and tournaments (includ¬ing many freeroll events) online.
Whereas most brick and mortar cardrooms offer a relatively small range of limits and perhaps one or two (if any) tournaments a day, there is a sufficiently wide range of games online that you can choose to specialise largely in tournaments, short-handed or heads-up play, pot-limit Omaha hi/lo or whatever else may take your fancy.
– You have a wider choice of opponents online.
Depending on the time of day and the limit involved, there are often several games available at the same limit, so you can select the best one according to your preferred criteria. Furthermore, once you are playing, it is easy to change tables should you decide that there is a better opportunity elsewhere.
– Online play offers a greater range of cardrooms to choose from.
Outside of California and Las Vegas, few brick and mortar players have the luxury to pick and choose between cardrooms, whereas online there are a countless number to select from. Many online players have accounts with several different sites, which enables them scout around for the best games at the click of a button.
– Most online sites offer the facility to play simultaneously at two or more tables.
In a brick and mortar cardroom you are naturally restricted to one table, playing maybe 30 or so hands per hour. However, online you can be seated at several tables at once, conceivably playing 200 or more hands per hour if you so wish.