there are lots of things that come to mind with this. how many tom's do you need vs how many you want. 2 up 2 down 1 up 2 down 2 up 1 down. transporting set up tear down will take longer etc etc etc
to me a 14 would be pretty sonically close to the other toms so I'd want the 18. i'm using a YD 16 in my set right now. It's not bad.
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