The Vibe got a lot of good reviews from what I can remember out of Consumer Reports, especially as a used vehicle, reliability and all.
Pontiac primarily went out of business because nobody was buying from Pontiac for some odd reason. They made a few good cars by the end of the division’s existence, but I don’t think that there was any realistic “appeal” for the brand. Tough, too, because they just put out the G8, which is a lot like the Vauxhall Astra VXR that GM only sells out of US borders.
I would agree with the others, though, that getting a cheap car for reliability should be high on the list, so the Matrix might be better for that reason.