VRL is one of the best private travel services in South India. Their buses are well maintained and the likes of Volvo are best in class. I have traveled in other private travel buses like SeaBird, Sugama, ABT, KPN , etc ... One think I find unique in VRL is its courteous staff..they never misbehave with their customers .. may be it is drilled into their work ethics when they are employed...
Other travels mentioned above, I have observed drivers and staff behaving as if they own the bus and may throw you out if they wish. Also VRL call center employees are very supportive and they get back to your query within an hour, which is not the case with others...Especially in case of refunds.
Also, when some of their buses are clubbed due to fewer seats booked, they make sure you are informed in advance and if you do not get the seat of your choice they apologize in a decent manner.
Few improvements needed in VRL:
They do not wait for 5-10 mins if you are late.. they used to do that earlier!
Sometimes they delay their buses to load the freight.
Hike the tariffs during weekend and holiday season, especially during Diwali they hike it by 50%.