Each of them reduces the bits in your fingerprint to some extent. Ghostery (and others that block third party requests) is reasonable if you trust the domain (not just the embedded objects in the page) you are visiting to not be interested in collecting data about you. However, if the domain itself is collecting data about you, then you have just provided one more bit of information that distinguishes you (since the percentage of population running Ghostery is smaller than the full population of browsers).

Secret Agent seems more reasonable in that it is actively targeted towards detecting fingerprinting. The way it works is by spoofing your HTTP headers, which are used in generating some bits to identify you. However, if you are directly on the internet (not behind a NAT (NAT is a way of sharing ipaddresses with others in the same network) -- being directly on the internet is rare these days), your IP is still accessible. If you are behind a NAT, you will have to trust your ISP not to track you.

Disconnect me is similar, and routes your request through a VPN, but you will have to trust them. (By routing your request through a VPN, they make your request seem to come through a different part of the world, than your original location, which removes one bit of information about you -- they do more, but this seems the most salient of what they do.)

NoScript works by removing the vector of many identification techniques, by disabling Javascript. However, it can also make your browsing experience painful if you are expecting dynamic look and feel in websites that are enabled by Javascript (you can whitelist, but how effective that is, depends on your browsing habits). Secondly, it does not eliminate all bits of identification.

All in all, all these are useful techniques, which can reduce the exposed bits identifying you to a degree (You will also have to trust the tool itself not to send any incriminating data back. There has been instances when these tools themselves turned traitor). They are all complementary to each other to a degree too.