I tried ML Sound Labs Mega Oversized and Freeman. Both great but I prefer the freeman pack. Later going to try the BGNR or BOANER and maybe ORNG pack.
As for bass, lollipopline has free IRs, SVT810_OlympicsIII is awesome with a Hartke 410 IR, latter not from shift line, because theirs sounded nasaly, but I will link in later when I get home, it is also free.
Heard that redwirez also make awesome IRs but haven't tried them so far.
IRs make a huge differrence in tone compared to stock cabs.