The "big 3" by most accounts currently are Softdent, Dentrix and Eaglesoft.
We recently did a switch from Softdent to Dentrix in my office. Short version as to why, is that Softdent just doesn't have the abilities to generate the reports that my partner and I want for a group practice, whereas Dentrix does. Softdent was however a decent program for my pre-partner days when the office operated basically as a solo practitioner.
Our price for licenses for 14 terminals, 2 days of in-office staff training, full data conversion and essentially all the bells and whistles that Dentrix offers (including their "Guru" feature which is basically a patient education program where not only can the patient view short video segements of procedures they need/symptoms + disease processes they have, but you can e-mail them the same video clips for their home use) was basically 14k.
A start-up solo practitioner will likely not need/want all the features that many programs have. However, as that practice grows and more providers are added, and more fees are generated, you may very well feel the need to change to a different program that will allow you to better manage and oversee the entire economic side of the practice from patient referrals to billing to collections and expenses, which can give you a better idea of where your money is going, where your greatest profit centers are and areas of your practice that are underutlized/under peforming.