Minimum internet speed required?

Hello everyone. I'm trying to decide wether or not to switch internet providers and need some help. I am currently signed up with Coxand (thanks to a promotion) my 18Mbps up/4 Mbps down I am paying $44 per month for internet only.

My question to everyone here is: Which speed would be best for my usage?

My usage: 2 iMacs, Macbook Pro, AppleTV2, iPad2, and two iPhones use the wireless network I set up with my Airport extreme and one of my macs has my media library that I stream to my TV. My wife and I aren't power users, but we are online students, use email, social sites, Netflix streaming, basic surfing for the most part, airplay/mirroring.

Cox is offering the following: 27Mbps/6Mbps, 18/4, 3/384Kbps

CenturyLink:40/5, 20/5, 12/5, 7/5, 1.5/896Kbps

I just want to know if I'm paying for a service that I am fully utilizing. Thank you in advance.

 

I know there isn't a right or perfect answer, and I have no problem waiting a little bit longer for things to load up. But given my usage, I didn't know if there was a minimum that my usage requires.

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So I guess this might be pretty obvious, but would you say the higher speeds are mostly designed for online gamers/torrent users/ and network guys as opposed to the average internet user like me and my wife?

I also put Netflix in there because I do like to stream video from websites like ABC on my iPad and mirror to the AppleTV2. I also have the wireless extreme base station from 2009.