Are Peavey cabs that bad?

I have used them for most bands I recorded (matching 6505 cab with Sheffields, to be exact), and they are rather good. There are other good cabs other than Mesa OS, you know. Dunno about cheaper ones, though.
 
I used to have a beaten up as fuck Peavey Valveking cab, nothing fancy but it had a suprisingly nice mid range, much prefer it to my 1960 speakers now in all honesty :(
 
Anyone tried the slanted 5150 cab? I got one but it sounds quite fizzy and honky in the mids, though it has huge low end if needed.
I should probably upgrade the stock speakers to sumthing with smoother high end and less honk. Any suggestions??