When it comes to engine strengths, almost all of the top engines you listed are going to be easily strong enough for most players.
Though whether paying for the likes of Houdini or Rybka is the right thing to do, is a matter of personal opinion, as there are doubts about the validity of their codes (I make no pronouncements on either, just pointing out that there ARE doubts).
However free versions of both are available - Houdini 1.5a and Rybka 2.3.2, and both are very very strong, you'd barely notice the difference between the free versions and the later commercial ones.
It really comes down to interfaces. Arena is free and works with all the free engines, and is pretty easy to use. Having worked with both Fritz and Aquarium I'd have to say I prefer Fritz for analysis, the different analysis modes (Full, Blunder Check and Compare Analysis) give different kinds of output ranging from Human readable text "White throws away his advantage" to lines of engine output on every move, which are all useful depending on what you are looking for.
I want to be able to analyze my games after I play them, but going through chess.com takes time.
I've noticed advertising for quite a few engines:
Houdini, Rybka, Chess-King, Fritz, Hiarcs and possibly others that I don't know about.
Does anyone have any experience submitting their games to any of the above and what do you think? Which one is the best - both in their analysis and their descriptions.
Thank you.