The DAX format is pretty much obselete now. It is slower to decompress whilst playing the game and slightly heavier on memory than CSO. It did have features for tweaking compression and leaving video/audio files uncompressed to reduce lag but both of these features are in CSO as well now thanks to kapoue3 and Cisoplus! which sealed the DAX format's fate (that and the fact there is no plugin for the custom firmwares, DAX is for devhook only).
JSO was created to try and be faster to decompress than CSO to try and cure the lag problem in the rare games that still lag on low compression (like the GTA games). Like the DAX format there are no plugins for the custom firmwares so this format pretty much dies too.
CSO has been the preferred standard for some time now and even though a few rare games like GTA do have problems i can't see this situation changing anytime soon. In fact if the CSO driver in the custom firmware could be optimized slightly to cure the GTA problem it would be perfect, though having the seen the source for the driver i don't think it wouldn't be easy to optmize. Who knows.
