What's a good valve spring compressor?

[ChallengerHK]

Title says it all 

[Chryco Psycho]

Manual or air ?

[Chryco Psycho]

Mancini has a tool that bolts to the rocker shaft pedestals , works on or off the engine , fast & reliable .
http://www.manciniracing.com/en2pivaspto.html this is for small block , they have one for big blocks too .

 This should work well http://www.tooltopia.com/lisle-16750.aspx but could be a problem with double springs

[ChallengerHK]

Manual for the moment, but I think you've answered my question. Thanks, Neil.

[Chryco Psycho]

this is a good C clamp type http://www.manciniracing.com/heavdutvalsp.html

[ChallengerHK]

What are the advantages and disadvantages of the different designs?

[Chryco Psycho]

C clamp type are what most shops use , but they need to be very ridgid as with high spring loads they will twist , the Mancini C clamp looks much more sturdy & should take a lot f spring pressure .
 The ones that bolt on the pedestals are may favorite as they are very sturdy & can be used with the heads on or off the engine  .
 The Lisle one also can be used on or off the engine but may not work with dual springs

[ChallengerHK]

Cool, thanks again.

[Chryco Psycho]

not as simple as you thought huh !!

[ChallengerHK]

I didn't think it was that simple, which is why I decided to ask