Any of the tubescreamer pedals will sound good if set right. They tighten the bottom, bump the mid & add more volume @ input. Try setting the pedal to 0 yes zero distortion, have the tone neutral & use the volume pot on the pedal to push those pre tubes
Also bias the amp hotter, this will get rid of some of the fizz & give you more drive in your tone.
DO NOT scoop the mids, the mids are where it's @ with these amps. Don't overcook the pre gain either.
The 5150 series is sensitive to tubes & gets a lot of it's gain from the power section not just the pre section.
I like the Tung Sol tubes in the pre section & either groove tube GE 6L6's in the (make sure they are the GE models the regular ones are shite), or if you want a kickass tone then spend the extra on a set of Wing=C= 6L6 tubes. They are fucking awesome. All tubes need burning in before they sound good as well, esp power tubes

What cab are you running it into?