You know I hope I am not talking out of turn here.
Playing chords is actually serious business for many people. Its actually not that easy to play a chord in any key at a moments notice without any sheet music in front of you and play it well. (usually you don't have sheet music but only chord changes for this type of thing.)
The only thing is, as a piano player you're not just playing a chord, your a playing it in a way so that it moves smoothly/nicely from one chord to the next. Also you are thinking what notes of the chord to play and which notes to omit, chord substitions etc etc. And all this has to be done as quickly as possible, in any key.
It might be better to practice instead not just one chord isolation but the ii V i pattern.
I also think that what you really need is someone to show you how to put the ii v i pattern together in 1 key, and the learn every other key on your own. When you're playing like this you wont have any picture in front of you, or notes, so its best to learn this type of thing without any notes or diagrams or whatever else. Its also best to learn this type of thing so you can play it as quickly as possible in any key.
Anyway just my 2 cents, I am not exactly an expert in the topic. I am sure some will disagree with the above. Kind of an interessting topic as my piano teacher makes me practise/drill ii v i patterns in every key.
b.t.w. I like the fact that you have the maj7, min7 and dominant7 chords listed
I've been working on an online chord practice application for some time, and would be very interested in your thoughts and comments, for further development..http://www.chordpractice.com
I'm thinking of adding scales and also a field where one can paste a song with lyrics and chords and be able to transpose the chords...
All feature requests and comments are welcome!