Which of Google Adsense Unit is Performing Better

There are five Google Adsense format. They are : Text Ads, Image Ads, Video Ads, Link Units, and Flash Ads.

TEXT ADS
Leaderboard - 728x90
Banner - 468x60
Half Banner - 234x60
Button - 125x125
Skyscraper - 120x600
Wide Skyscraper - 160x600
Small Rectangle - 180x150
Vertical Banner - 120x240
Small Square - 200x200
Square - 250x250
Medium Rectangle - 300x250
Large Rectangle - 336x280

IMAGE ADS
Leaderboard - 728x90
Banner - 468x60
Skyscraper - 120x600
Wide Skyscraper - 160x600
Small Square - 200x200
Square - 250x250
Medium Rectangle - 300x250
Large Rectangle - 336x280

VIDEO ADS
Leaderboard - 728x90
Skyscraper - 120x600
Wide Skyscraper - 160x600
Small Square - 200x200
Square - 250x250
Medium Rectangle - 300x250
Large Rectangle - 336x280

LINK UNITS
120x90 - Displays up to 5 links
120x90_4 - Displays up to 4 links
160x90 - Displays up to 5 links
160x90_4 - Displays up to 4 links
180x90 - Displays up to 5 links
180x90_4 - Displays up to 4 links
200x90 - Displays up to 5 links
200x90_4 - Displays up to 4 links
468x15 - Displays up to 5 links
468x15_4 - Displays up to 4 links
728x15 - Displays up tp 5 links
728x15_4 - Displays up tp 4 links

The question is, which is giving the best result for publishers? Is it with images? Or Text is will be enough?