Quake Live is a combination of classic Quake 3 Arena and Quake 3 Team Arena, originally a browser-only game which then later got turned into a standalone application available on Steam. Quake Live is considered to be one the most successful competitive 1v1 eSport of all time.
Pro Extremely dynamic and very fast-paced
Quake is known as an old school arena shooter, where fast paced action and dynamic play is the norm. Being dynamic gives advantage to no one, keeping the game completely skill based. Adding on top, the fast movement of the players characters creates an environment that requires practice in order to get skillful enough to compete. This creates a game where getting to the top is a tough battle that many strive to achieve.
Pro Active, well-supported eSports scene
Quake Live has a very active eSports community, with current numbers (as of Oct. 2016) showing that the top players are earning over 6 figures yearly.
Seeing such large a sum means many people will be interested in competing, making for an active community surrounding the tournaments held.
Con Dumping ground of failed business models and platforms
First we had a browser-only F2P model which was monetized by ads, then we got a F2P model with a premium/pro subscription modes with limited/circulating content for free players, then we got a steam only release, then we got a Steam only release with a $10 paywall. The game now ironically feels more free than it's even been. If they had chosen this model right from the start, potentially they could have put more focus into advertising/distributing the game which could of contributed into the game being more popular today.