Hi,
I have the Kenwood Cooking Chef as well as the Thermomix. I have also just purchased a Thermochef to trial as a possible machine for our business to sell......we have had a few enquiries about Thermomix's which we have had to pass on to Thermomix. I will be able to post a comparison of all the machines in a couple of weeks hopefully.
I love having both the machines. They both have good points and bad points. The Thermomix is great for a convenience factor of having the built in scales and being able to use the one jug to do almost everything. The Kenwood is good because it has a larger volume and it is easier to clean when doing doughs...I can also do larger volume dough and I can use it in winter to prove the doughs as it has better temperature control to a lower and higher temperature. The disadvantage is you have to have "accessories" to do different things....but it does come with a food processor and blender attachment. It would be better if it also included the milling and mincing attachments. It also has very little in the way of recipes that come with the machine, but I have been able to adapt most recipes to it fairly easily.
I don't know that I would like to have to try and choose between the two of them. I usually have one machine doing one thing and the other doing something else. The only thing I prefer between the two machines is that the Kenwood is easier to clean when I am doing multiple lots of doughs. I would probably select the Thermomix again if the two machines were put next to one another at the same price point purely because it takes up less room on my bench. I paid $1500 for the Kenwood this time last year and I have had the Thermomix for about 2 years. I'm trying to work out where the Thermochef will temporarily live in my kitchen. After Christmas I will probably have to take it to our demo kitchen for our salespeople to play with, but until then......I NEED a bigger kitchen.