We are planning a kitchen remodel and are looking to replace some existing appliances. We have a 36" cooktop and downdraft currently. Not a huge fan of the downdraft and find it very inefficient. Ive heard that you have to have some sort of ventilation system though. Not sure how truthful that is but figure I should put some sort of ventilation back in so will likely go with another downdraft. I like the look of a range top and thought about switching to one. Ive researched the GE, kitchenaid, and thermador versions. Would appreciate any opinions and first experience.

If you're using a range with a built in vent, most are POS and don't do a good job. JennAir has a 36" one that's ok, but that's it. The separate vent walls are the way to go.

I've used the KitchenAid walls in a couple remodels and it's been a good system.

And you do have to have a vent per code.

Ductless range vents would by definition not need to be vented to the outside. I would need to double-check, but a ducted range hood needs to go outside and not the attic, like fart fans.

Ducted vents leading to the outside allow a house to "breathe" and overall are much more preferrable to a ductless (I would categorize ductless and worthless sorcery that accomplishes... not much).

Our current setup is a downdraft that has a duct system and vents externally. Main issue is it doesn't move much air. I've seen some larger blowers that move a greater volume of air. That might be the solution. Just not satisfied with our current system and wanted some suggestions before we buy anything. Thanks for any help

In ALL designs, any downdraft needs a ceiling exhaust #2 to grab what rises quickly & escapes the reach of the downdraft.

We offer "make-up air" appliance options so the external exhausts can fully expel up to their rated CFMs, some are less than $100.

Indeed a larger CFM rating can help and so can replacing the downdraft hose/pipe with a) larger, b) smoother inner surface

As for brands, Consumer Reports has their best picks.
Our 1980 K-A downdraft range is the only appliance never replaced and works fine.