I have seen a few T&S machines - but have only seen one or two models I liked. The 600 and the 603 seem to be decent machines as long as the bobbin winder work - you also need to have perfect bobbins - anything wrong and they don't work right. Also you have to follow the bobbin winding directions perfectly.
As far as Kenmore there are many nice old Kenmore machines - I have noticed that the reverse button tends to freeze & bobbin winder's break