I just bought Cro-Mag last week after the price dropped again - and I can't understand why people rate Crash Bandicoot higher (I have both). Cromag has better graphics, better sounds, and is a lot "wackier" with OTT physics. At less than two yoyos here, it's the best value game I've bought.
Although Cro-Mag is only $1.99, I think the reason Crash gets a better rating is due to several reasons.
At the time of release, both were priced at $9.99 so the comparisons were more level at that time.
From what I've read, the edge in graphics may go to Cro-Mag, but it seems that there's no "purpose" to playing it. In that, I mean, it doesn't keep your best time, there are no levels to unlock, and nothing to keep you playing towards. In essence, there really isn't any goal other than coming in 1st, and after each race, it's over.
On the other hand, Crash has a challenge mode which keeps you coming back for more with a purpose, a goal in mind, and that in itself is probably why it gets it's better rating.
Now, is Crash at $9.99 a better buy than Cro-Mag at $1.99? That's an entirely different question....