I stand by the side of Peavey on reliability. I think the comparison is between the same price range item.
If you compare, the AVT20 is at power output of only 20watts, but the bandit is at 80watts. The volume difference is quite great.
Apart from the single 12AX7 preamp tube, the marshall features are standard of small amp. For Bandit, you can shape the sound between clean and 3 select on lead channel, output also got resonence and damping adustments. So tone wise, I think you can get a whole lot more range on the bandit.
But if you are just using it at home and you love the marshall tone. Then go for the marshall.