Twitch has spent considerable effort building out its infrastructure, which has resulted in higher stream quality and better transmission speeds for its streams.
Twitch has native apps for both Android and iOS, as well as others, such as its native app for OUYA. Its popularity also means there are several unofficial apps for platforms like XBMC and Chromecast.
Twitch was one of the earliest video game streaming services, being spun off from Justin.tv. As a result, it's steadily built a large community, further boosted through e-Sports related partnerships. As a result, there are plenty of streams to watch at any time.
In the past, Twitch has had multiple incidences of site admins abusing their authority. The most notable event was related to admin 'Horror' banning multiple accounts for personal reasons in November 2013. The initial response from the Twitch team was to defend the admin, exacerbating the situation.
As of August 6th, 2014, Twitch has imposed a ContentID-like system to detect copyright infringement in the audio of videos on the site. As a result, a surprising number of videos have had large segments, or the entire video automatically muted, even for just playing the in-game audio, regardless of whether or not the streamer has the rights to play that audio.
Since an update in late 2013, streams have a delay of up to 60 seconds, in order to help improve video quality across the site. While this isn't likely to effect large eSports events, it has a severe negative impact on streamers who directly interact with their viewers.
Since Twitch implemented an up to 60 second delay for all streams on its service, this has become a notable feature. This issue is particularly important for streamers who interact directly with their viewers.
Hitbox.tv's website is responsive and convenient - users can easily do things like browse for other streams while keeping their current stream open in the same window.
Users of both the mobile version of the site and the current (beta) version of the Android app have issues with viewing streams as well as the chat. Reviews on the Android marketplace reflect this.
As Azubu focuses primarily on eSports, and is curated and moderated around this content, streams are very well organized. It's immediately apparent who the most notable streamers are for each game.
As streaming is curated, rather than open to any broadcaster, the amount of content is severely limited. Azubu isn't a place where you can watch 'Let's Play' videos, blind runs, or casual races and speedruns.