I own copies of ALL of these programs and if you want to do Comparisons I highly suggest UltraCompare
If you want to do very complex changes then I'd go with PowerGREP (hi learning curve but very powerful).
UltraEdit also provides Regex operations and is one of the most powerful editors on the market.

UltraEdit / UEStudio / UltraCompare[/color]

[color=green]PowerGREP: Taking grep Beyond The Command Line[/color]

[color=green]RegexBuddy: Learn, Cr...ular Expressions with RegexBuddy



If you have the new MS Windows Search 4.0 installed I recommend you uninstall it. Searches are very limited with it installed now. Indexed data is found fast, but they don't index everything even if you do tell them to.