I have the estring, been using for the past 6 months, and love it, do not feel it at all once it's in, it fits similar to a diaphragm, never had any issue with it at all.
It can be removed and reinserted as and when, and can be rinsed under warm water.
Much less messy that estriol cream I was using before, can't comment re vagifem as not used that.
I tried a couple of weeks without estring, after my GP suggested it might not be necessary as well as tge oestrogel. But I found soreness during sex returned, so now back to using my estring.