Big boxes w/ chicken knobs look solid. I don't know why but to me, while being more real-estate economical, the smaller ones seem to look like their wide base knobs are too close together and could possibly come undone by an errant foot. I don't really think they are flimsy of course - just purely going by aesthetic impressions.
I've always associated Cornish pedals with the "regular" look, which gets my vote. Not really like the black box design, nor the Fender-type knobs. That said, size is a factor to consider and being that most folks use power supplies, a battery-free smaller grey box would be ideal!
I prefer the big box look and the option of using batteries, but I would prefer to have the numbered "Fender" knobs, rather than the standard chicken head knobs.
Like the looks of the old greys, but can't beat the small box ergonomics. If I could find some smaller chicken heads to fit I'd be 100% happy. Much harder to see your settings with the Fender knobs.
I prefer the small because they are smaller (duh) and have top mounted jacks for my pedalboard, but I do think the bigger ones have the classic look. But still, I prefer the old because pedalboard utility is more important for me than overall looks.
But anything else that's barely bigger than a Boss pedal, I get the cliche "I don't have a square to spare" type response when trying to do various trades and etc...
I don't get this place sometimes...
Then again, if you're dishing out $800+ for a single effect then you better damn well make room for it!