I was, and am, far from enamoured of the EU, and was genuinely on the fence at the start. However, I will now almost certainly vote to stay in, because no even vaguely acceptable alternative is available. To vote to leave has become synonymous with a vote against immigration, against workers' and environmental protections, and for economic neo-liberalism. It's very clear that all these - laced with coded and not-so-coded racism - are what we'd get in the event of an Out vote.
It absolutely didn't have to be that way: there are other models that an independent Britain might have followed, but at this time there is no group both willing and able to bring them to existence, or even to talk about them as a possibility. So, the choice is: EU, warts and all; or else a UK stripped of everything that's actually valuable and worth having about the EU. It's not really a choice, is it?