The best one? A live doe walking by herself in the November woods twitching her tail and frequently stopping and looking back where she came from. If she's just come from a scrape then that's all the better.
Anything other than that is pretty much marketing hype. Take a look at this thread....viewtopic.php?f=66&t=936
We pretty well fleshed this one out a few years ago here.
Bottom line.....the deer scent industry is probably the biggest scam in deer hunting right now, even since ScentLoc/Block got exposed in court for the liars they are. The scent industry operates with NO standards of collection, purity, or even a standard DEFINITION of what they proport to sell! It's irrelevant anyway, because if it's urine based, and it comes out of the bottle brown/amber in color, then it's urea by that point.
I tried them all over the years, Code Blue, Tinks, Matriks, etc. I used droppers, film cannisters, cotton balls, scent drags, scent wicks, sticks, and God knows what else. NOTHING worked. Not once. Not ever. The walked by it, around it, under it and through it. Nothing. Just ignored it. So I decided to stop wasting my hard earned $$$ and now all I ever do is urinate in scapes myself, and you know what? I've gotten more positive response from that than ALL the commercial $cents I've ever used combined.
Read the thread and decide for yourself.