This is a great thread!! So many options out there.
I bought a JennAir semi-commercial gas convection range two years ago. It replaced a GE coutertop gas cooktop and electric wall oven, neither of which were anything to write home about. Personally, for various reasons, I think they both sucked.
It has 17,000 and 18,000 BTU burners in front, and 6,000 and 9,000 BTU burners in back. Far bigger than the standard 9,000/12,000 standard burners most gas ranges provide. The two front multi-tier burners will boil large stock pots of water faster than any electric stove can. But there is a price to pay: it puts out more heat than the furnaces of hell, unlike a smoothtop range that just heats the pot, and not the air around it. Cooking on it in the summer is possible only with the air conditioner on. The cast iron grates retain so much heat that you have to remove a pot from the stove to stop boiling quickly, or try to slide it to another burner, which isn't as easy as it sounds across the heavy cast iron grates. The cooktop control is second to none, as far as boiling all the way down to simmering, but only the simmer burner can give you a true simmer. The rest of them produce too much heat even at their lowest settings, but that works well for general cooking. I guess that's why they call it a "simmer burner".
The broiler is nothing short of perfect - no electric oven I've ever used can broil as fast or as much so quickly as this thing can. But again - it puts out more heat then the furnaces of hell, especially when the cooling fan that cools the electronic control panel comes on, which is about 5 minutes after the oven heats up.
The convection oven itself if fairly quick, even, easy to use and dead accurate, but at temps above 325 degrees or so, it heats up the room like a small furnace - and I have a big kitchen. Timing is tricky - it seems to cook everything far quicker than standard cooking times given, though the temp is dead accurate throughout the cycle. The oven cleans well inside, takes about 3 hours per cycle for heavy soil, but we won't talk about the heat this thing puts out while it does it.
Cooktop cleaning isn't awful, and it's not great. It's just okay. An electric smoothtop is far easier to clean than this thing after cooking/frying or even boiling! Its burner surface shows every streak, spot and mark. The range is stainless with a black burner surface. It shows every speck of dirt, grease or grime, though the cast iron grates are surprisingly easy to clean.
Bottom line - it cooks very well, does what it's supposed to do, but even with high end ventilation, this thing puts out some major heat, and that's just not an issue with an electric smoothtop range in my experience. It's much, much easier to burn yourself using its cooktop then it is an electric one - as it heats up handles, lids and everything around it, so it's not for everyone.
Performance does come at a price! I can't say I would buy it again, can't say that I wouldn't - always fun to try new "toys". I have both a gas line and 220 supply at the stove, so I can have whatever I'd like there. But I like it, a lot. And I pretty much cook every day - not the "heat and eat" type at all. But it takes some getting used to, that's for sure.
