It's a fair question Doucas, although I don't really like the archaic terms of Brexiters, Remainers etc..it's all a bit divisive and most people don't define themselves as such.
Nonetheless, as someone who voted Leave in 2016, I would seriously question it if:
Major economic metrics were negative when comparing UK with our EU peers..lets say France, Germany, Netherlands, Belgium, Sweden, Italy etc.
The major metrics I'd consider are things like unemployment, wage growth, GDP growth, inflation, stock markets, currencies etc. Things like that.
Now on those metrics, on some cases UK looks less good, on others better, but generally speaking there is no clear economic difference between the UK and those countries, there simply isn't. Our unemployment isn't higher, our inflation isn't higher, The FTSE isn't struggling more, our currencies are all weak, GDP growth is broadly comparable.
Other metrics of course exist, there are dozens and dozens of them, but fundementally they will feed into the major ones above.
I'd also question some of this. UK exports are at a record high, and you can actually see a rise that begins after 2016
https://tradingeconomics.com/united-kingdom/exports
https://www.gov.uk/government/news/u...at-record-high
I do agree that trade between the EU and UK will never have been easier than when we were members, but most businesses don't trade with the EU and the counter argument to that is that trade with non EU countries
should become easier - and this is where future global growth is likely.
So, that is how I would assess it, and as others have suggested, it's not all about economic matters - the freedom to develop our own laws is also a big thing, and I am particularly interested in how we can pay farmers to better maintain their land etc.