http://www.lovehoney.co.uk/product.cfm?p=34953
This is the best I tried so far, fits really well and feels very good, if someone owned this, have you tried anything that's even better than this one? Please let me know, thanks.
I've not used that nor the one I'm about to link to, so feel free to ignore me, but I think the natural next step is a metal cock ring...
http://www.lovehoney.co.uk/product.cfm?p=33583
Never been too sure about the metal cock rings.i know they look good but are they effective at providing the construction that the stretchy cock rings do?
Yes, I was just asking maybe someone tried this or similar rubber ring that not just a standard round ring and goes through more than one place, maybe has a vibrator function as well.
If you choose correctly metal rings are around superior to stretchy rings. They do not stretch, they can be cooled or heated, they are much more durable and they look a lot better.
So choose one that you'll be able to get into when flaccid but that will offer the required squeeze when erect.
As regards the OPs question - try the reviews. Visit cock rings page, sort by average review and take a read through the highest rated ones.