All these switches are new to the market in 2017 and has very rich capabilities. Cisco 9300 and 9500 are fixed Chassis and 9400 is a modular chassis. If you want to have the switches in Stack for Access, go for Cisco 9300 with maximum of 8 stacks. If you want modular instead of 4500 then simply go for Cisco 9400- C9407R model with 7 slot chassis.
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