Eggs – What qualities should one look for when choosing Egg cooking gear

Look for a strong motor and thick blades. If the blades are thin, they're likely to warp over time. The motor needs to be able to spin those blades through the liquid.

Look for a thick glass container. The plastic ones are unlikely to deal with the heat of things like soups and sauces being dumped in.

Check the gasket between the glass container and the piece that attaches the blades. A thin, flimsy gasket is likely to start leaking before a thicker, softer gasket.

Look at the number of teeth on the connection from the motor to the blade. The more teeth, the greater the surface area being used to distribute the power to the blade mechanism and is less likely to wear out.

Overall, as with many things, one of the quickest ways to tell a good one is to weigh them both. The heavier item is better. No one pays for shipping extra weight unless it's there for a good reason.

(note that the "heavier" rule doesn't apply to electronics like cellphones/computers, etc. where the cost of making it small is actually higher)

Great french toast starts with the bread. You're looking for two things: thick slices, and staleness. Why stale? Stale bread has enough firmness to stand up to the custard. If you don't have stale bread available, you can set it out the night before in a simple wire rack. At least 8 hours should be enough to stale it up nicely. They will be rather firm to the touch.

The ideal finished product is crispy on the outside and creamy in the middle. This might be what you mean by mushy, but mushy in my mind is kind of negative. The key to accomplishing this is to let your bread soak in the custard only 30 seconds per side, but then move it to a rack to sit for another 2 minutes further. This extra set time allows the custard to penetrate deep inside the bread, and be distributed much more evenly.

The final trick to getting a nice crispy crust, is to cook it twice. First in the pan/griddle as you normally would, but then 5 minutes in a 375 F oven on a rack. This brief oven stint crisps up the exterior nicely.

I highly suggest watching Alton Brown's Good Eats: French Toast episode. That's where I learned the oven trick, and his recipe hasn't done me wrong since.

Regarding challah, I've never had it, but based on the Wikipedia description it sure sounds like a good candidate. Just make sure you slice and stale it overnight.