Navi-X is a great addon to XBMC. It has almost anything you could want in an addon. The only drawback is that the XBMC Navi-X Addon is slow for me at times. It is also very hard to keep things organized when trying to watch seasons. There are some great alternatives to the XBMC Navi-X addon that I will list below.
1Channel Addon – This is a great xbmc addon when it is working correctly. Mostly standard definition stuff though. It does have almost anything you could want.
Icefilms Addon – This is very good for High Def videos and shows. Although lacking older seasons and hard to find movies, still a good choice.
Project Free TV Addon – Great to see what you may have missed. With one of my favorite features ‘Last 24 hours’ or ‘Last 3 days’ you can easily catch something you may have wanted to watch but just didn’t know it was on.
MashUP Addon - MashUP is a good new addon. It has A LOT of content and may require you to look up the new install method as of recent. They have done some advertising and popups which I am not entirely fond of. All in all it is a good source.