Unless you are talking about absolute brute power output then putting together a list of the "Top 5 Overall" amps would be next to impossible.
There are far too many products available that are more than satisfactory at doing the job they were designed to do to be able to narrow it down to a list of the Top 5 excepting the single qualifying factor I mentioned above.
As already stated - this is an incredibly vague question as well as one that gets asked with far too much frequency.
Flamefest ON! LOL!