Personally, I will vote to remain within the EU.
Firstly, the two biggest issues which stand out to me as possible justifications for staying within the EU - immigration and national sovereignty - are ones which aren't major issues for me personally; in fact, in some ways, I actually view the immigration provided by the EU, and the loss of national sovereignty as a positive thing in a way.
Certainly, we need immigration (to an extent) to support our aging population and to promote economic growth, though of course more of the issue is to the extent to which this is necessary - undoubtedly there are negative impacts on lower skilled labourers, which is something of concern to me (though I won't pretend that I'm not somewhat detached from this issue; and I certainly do not care for any claims of so-called 'damage' to British cultural homogeneity)...but the economic benefits appear (for me) far too great to use this as a justification to leave the EU.
And leaving the EU would also be bad as, in an age of globalisation (and at a time where cliamte change is becoming an ever more prominent issue), we would lose access to a framework through which European states can effectively act in a collective manner; Britain's exit, as well as damaging this in and of itself, could also hurt further efforts to promote collective international action, which is of course more difficult outside of a sovereignty-taking organisation like the EU and which is of vital importance.