In.
The benefits of the EU vastly outweigh the detriments.
Benefits: trade, single negotiating force, political clout
Detriments: loss of sovereignty in some areas
Both Britain and the EU are stronger with Britain part of the EU.
Both Norway and Switzerland have terms dictated to them by the EU without having a say in how the EU is run. Just look at how implementation of the 2014 Swiss referendum limiting the free movement of people would result in the Guillotine clause collapsing the other six Bilateral I agreements*.
I would rather have terms dictated to me by a club I belong to than a club I do not belong to.
*
https://www.eda.admin.ch/dea/en/home/europapolitik/ueberblick/bilaterale-1.html