More like apples to light bulbs. The Sonic and Spark are entry level GM products, the Prius is a mid level Toyota. GM blows.
Depends on what you're comparing. If it's TCO then you'll never get a good answer. If it's handling, I'd put ten down on the Sonic, because the Prius turns like a toad. If you're comparing interior appointments, then the Sonic had better seats, but the Prius is probably more comfortable overall. The Sonic has a better radio. If you're into the bunny-hugging thing, the Prius is rather iconic in the green world for a pretty good reason. If I were looking for a committing car that I was going to keep for more than three years, then it would be the Toyota, hands down....especially on the interstate. ALL cars are boring to drive on the interstate! The Prius is probably more reliable than the Sonic, but the dealership network is a little bit shiftier. If you get a Prius...or any other Toyota product you'd better educate yourself on the schedule of maintenance!!! This is true for all of the OEMs, but I see it a lot more often in VeeDubbaya's, and Yotas. Like I said. It all depends on what you're comparing. What kind of answer did you EXPECT in a forum called PRIUS CHAT? YMMV!
Not even close to apples to apples. Let's see.. you're comparing compact and subcompact 28-32 mpg combined vehicles to a 50 mpg combined midsized car. See Compare Side-by-Side and the specs tab there. Perhaps the compact 50 mpg combined Prius c would be a closer comparison (Compare Side-by-Side).