Here's a thread I had posted about this issue: Rybka 3 Aquarium or Rybka 3 Chessbase version? I want YOUR opinion!
GUI's compared

I was at one time heavily into engines, and so I have at least some experience with a multitude of GUIs. Winboard (stable but boring and limited), Arena (nice, but lacks support bigtime), Chesspartner (one of my favorites for logging my engine onto the Internet - the problem is that it and Arena do not support variants, and Winboard does), Fritz (by far the best for personal use), ChessMaster (awesome interface for lessons and general fun), Blitzin (Great for ICC), Dasher, Thief (simple and straightforward, wonderful interface), BabasChess, and I'm sure several others throughout the years.
In short, Fritz wins hands down, with Chesspartner coming in a close second.
Did you have any specific questions?

I found Fritz to be a little hard to learn, it was not obvious how to do things, but once I did learn it became easy.

Yea Fritz is a very complicated program with a LOT of options, but in my opinion, it is well worth the time it takes to become acquainted with it. Very powerful.

I like the new Chessmaster: Grandmaster Edition for general stuff, just playing a quicker game against opponents of various strengths. It also has great lessons & natural voice analysis so thats pretty nice. But I think the program is pricey & it's f'n huge file size.
I like winboard since its barebones, small & simple and can analyze games with lots of engines.
I also use Arena which is a little more advanced than winboard but not as user friendly.
I guess as far as fun & gameplay go Chessmaster is killer but for basic analysis winboard & Arena do the job just as well with much smaller file size.

I am a beginner and I own Fritz 10. As a GUI for analysis purposes, Fritz is awesome. It looks very nice and I have found it to be really straightforward to use.

I have Chessmaster Grandmaster Edition, and it is worth it for the Josh Waitzkin tutorials alone.
I guess my intention was a discussion just of the GUI's you can use an engine with to analyse your games and make and explore databases, etc. You can't do that with Chessmaster... can you??
So does everyone that says Fritz mean Chessbase? Or can you store and analyse games with the Fritz GUI?
No votes for Aquarium yet, anyone have experience with it?

Yes, Chessmaster can do that! Did you buy yours new, so that you have the instruction manual?
Fritz is far superior, but Chesspartner, Arena, Winboard and Chessmaster can all do those actions. :)

no i didn't get an instruction manual, but i imagine it must be online somewhere. thanks for the tip!

I like the Shredder GUI as it seems to be the most utilitarian which allows me to get right to work or play. I have tried all of them and always come back to the Shredder GUI. It is also very stable.

Fritz 12 will be out in 10 days. I will have ribbon menu bars like MS Office and seems to looks a little bit like the Aquarium GUI.
I've owned every Fritz since version 3 and the GUI has become a little better with every new release. It is stable, easy to use and looks very nice and professional.
Aquarium on the other hand has tons of additional functions, especially when it comes to analyzing. The support forum is excellent and the developers haven an open ear for user demands. To me this GUI is the very best. But there are two drawbacks: chessbase engines are not supported and you will need quite some time to get used to every function of the programm.
Arena finally is professional to and it is completely free.

it is possible to try out the aquarium GUI as a free demo download from the rybka home page. i'm not altogether sure that all its features are made available in the demo version but it does give a good overall impression. personally i tend to use ARENA in the main as i mostly use a GUI for analysing my ICCF games and ARENA seems perfect for this task. of course it lacks a lot of the features and support that some of the other GUIs have, but for my purposes it is ideal and graphically it is very good as well. it is also capable of analysing using 3 engines at the same time.
How about Deep Shredder and Exachess GUI's? Does anyone use them? I have a recent model iMac, and I had decided to use the Sigma interface with HIARCS 12. Right at that time the Sigma interface turned out to malfunction with the Mac. Now I need a different GUI, and it needs to be compatible with the Mac as well as useful for analysis. I have since discovered that many of the GUI's won't run with the Macs.
Any comments?
I thought I would start a new thread specifically about the GUI's [Graphical User Interface - the program you actually interact with, as opposed to the engine which just powers the analysis, for those not up with the lingo], because general discussions about 'Fritz vs Rybka', 'Fritz 10 vs Fritz 11' etc seem to be largely about which engine is stronger, and does that really matter to amateur players. It doesn't really matter to me - I'm not a titled player and never will be, so sure I would like to have a strong and fast engine to analyse my games, but at the end of the day it is about the GUI I use: is it easy (and even fun) to use, thus encouraging me to study harder and analyse more of my games, or is it a pain in the ass that I can never quite figure out, thus discouraging me?
I have only ever used Chessbase 9, and my experience is mostly the latter (which is why I am looking for a new GUI). (To be fair to Chessbase 9, I haven't put in all that much time and effort reading the manual and trying to figure it all out).
So it would be great to hear from people who have used more than one GUI who can offer comparisons, or from people who have strong feelings about the one GUI they have used. Thanks.