The Big Dog looks like high quality. Definitely a nice feature to have a tilt up deck. But it also looks like you're paying too much for the electronic features. I'm not much into all the electronics on a mower; just seems like overkill that will end up hurting reliability. But then, any mower built in Kansas is high quality in my book.
Spartan also seems like electronic overkill. Paying too much for added complexity that won't help function or reliability.
Can't go wrong with a higher end Toro. Though I wonder about that funky new ride system they have. Definitely would want to test ride one first.
I like the toro, but recently found the engine is made in china..