I'll make comments on each of these typing test sites - I may leave out lots of stuff though!
At this site, they have a number of texts you can type as well as an option to enter you own text - though, as far as I know, you can't have multiple custom texts that may come up randomly. Just one at a time. I have found on some of their text examples, I'll get to specific spots where the keyboard stops working. Once I learn which ones do that on my computer, I just skip them when they come up. You can also set the timing limit. Letters appear right on the text, but it doesn't show what you typed when you make an error. It just shows the error in a different color. At the end, it gives basic stats (wpm, accuracy) and also correct entries, incorrect entries, fixed mistakes, error rate, etc. Also info about the top three missed characters and most inaccurate (based on percentages. I've generally liked this one.
Shows what you type belot their text. If you make an error, the text will change color and stay changed for every letter in a word after the initial error unless you delete and correct them. Not timed - just finish the text presented to get speed and accuracy.
This is another part of the Keyhero site above - instant death. Frustrating if you make mistakes very often since the round ends on the first one! I do like it, except for how they calculate things. It seems that if you make an error, it treats everything after the error as also being wrong. So you get really bad WPM scores. I wish they'd also give the score for how far you got.
Random words. You don't see any score until you are done (I prefer to see it as I go). What you type appears below the text box. If you make an error, the whose word changes color, not just starting from the first wrong letter.
Never did one much and haven't for a long time so I don't recall much about it.
This is for dvorak users. Your words appear below the text box. If you make an error, the error shows for that specific letter, but you can't go further untis the word is corrected - any time you hit space on an error, it will jump back to the start of the wrong word.
Your text appears below text box. Wrong letters change color, but whenever you hit space, the cursor jumps to the NEXT word. Stats and "time left" show as you type, but in small print so mostly not useful.
UPDATE: One nice thing about this test is, when done, it shows you the words you missed AND what you typed! Very nice for catching patterns of errors. However, it only shows words you didn't correct so if you go back and correct a word, it won't show up in the list.
Lots of good stuff, though some things bug me. Doesn't use real words quite often. Since a good typist tends to think in words rather than letters, this is annoying. Also, instead of a plain space, they have a special symbol which, to me, makes things harder to read. Each test is really a short like of text. You can make it longer or shorter, but you aren't looking at 1 minute tests or longer. stats are extensive, but to see most of them, you have click your "profile".
Handy for some things - especially entering custom text - but the timer doesn't start until you click the start button and then you have to drop the mouse and start typing. That takes time and thus throws off your score.
Hopefully others can provide more info on each of these or add more to the list.