What is your most favorite software and what is your least favorite?

: What is your most favorite software and what is your least favorite?
This can be any software free or otherwise. Just list some software and maybe show this question to others and ask them and then answer. Some of my favorite software are Open Office, Advanced System Care 3, VLC Media Player and more.Please LIST them and maybe explain why.

Answers and Views:

Answer by Robin B
Least favourite – Internet Explorer (whatever version) – slow and unresponsive.
Favourite – Firefox for the opposite reasons.