Which is best ibm thinkcentre or hp?

It is actually now Lenovo Thinkcentre, and depending on the survey, they almost always get higher ratings than HP. You also have to consider models.
Here is one survey:
http://www.pcworld.com/...rades.html
Lenovo shows as combined consumer and Thinkcentre business where HP is split.
Here is a review of one model:
http://www.desktopreview.com/default.asp?newsID=760&Review+Lenovo+ThinkCentre+A58
In energy efficiency, most Lenovo are highly efficient and the wattage would need checking by model for each PC of each company.

IBM Thinkcentre is more economic and energy efficient. The most important thing about IBM is that it is build strong and is more than just reliable. I bought one for my kids and it works flawlessly and quick fast.