Best firmware to jailbreak?

[Shwonx]

I've been out of the loop for quite a long time. I'm currently jbed on 3.1.2 and I wouldn't mind updating. I have my shsh saved for every firmware since 3.1 so I'm wondering which firmware provedes the best jailbroken experience? Also, which jailbreak should be used?

Ps. I have a 3gs.

 

[Applejuiced]

If you have the old bootloader 3GS go with 4.2.1
If its the new go with 4.1 so you can have an untethered JB.