I'm very happy with my Jager. I haven't used a stealth, but I think if I buy a new one (fat chance, since I have two or three extras already) I might try the brand, since everyone's happy with it. But I have zero complaints with the Jager, it's easy to set, I like the black look, and it hasn't died or had thermostat problems (although I would recommend using a real thermometer to check any heater, the dial can often be innacurate).
Actually, I can see buying one if my oscars finally manage to kill the heater they have. The plastic casing would be good for them. But I don't think you'd regret going with any of the name brands at this point, I'd just avoid the $10 Wal-Mart bargain bin ones.