I will comment on the science of this…
Hops have many specific aromatic contributors that can favorably affect a beer’s aroma if utilized properly. The most important contributor when it comes to delivering that blast hop aroma is a hydrocarbon compound known as myrcene.
Myrcene is an important part of the essential aromatic oils in hops. Perfumeries frequently harness its power. And commercial American IPA brewers strongly favor hefty late and dryhop additions of high level myrcene hops like Citra, Amarillo, Simcoe, Centennial, Nugget, US Northern Brewer, and Horizon. Other hops like Columbus, Summit, Galaxy, and Chinook have moderately high amounts myrcene while still having very high total oil levels. The interesting thing about hops like these is that despite having high total oil levels and high myrcene, these hops tend to have low levels of caryophyllene, humulene, farnesene, and selinene. The opposite is true for European Noble hops which have low total oils, low myrcene, and moderately high levels of everything else.
Myrcene is highly volatile and subject to heat and oxidation. Thus it is found at very low levels when used early in the boil, but the levels are much higher during mid flameout and dryhop. A 60 minute hop stand during mid flameout (anywhere between 100-150 F) have provided the best results for me. This is easily attained by using a slow-cooling ice bath as opposed to a fast cooling wort chiller. I do this in my stainless steel sink, which covers the kettle about 3/4 of the way with ice-water. It quickly melts so you really need to keep re-icing to realistically cool it in one hour. Don't be afraid of adding ice. The kettle will be primarily covered to aid sanitation (aside from 2 or 3 short whirlpools). A covered kettle is necessary after the boil, but it retains a ton of heat.
I’m so glad I did not buy a wort chiller because I would have never stumbled on the benefits of a long hop stand, which has given me insane hop aroma. I always couple a long hop stand with a substantial dryhop at the rate of 0.50 to 1.00 ounce hops per gallon of beer (0.65 average), depending on gravity, time, and technique of the brewer. So both techniques in combination have really worked to wow me and my friends.
As with most other aspects of hop quality, there is a difference between whole hops and pellets as well. Whole hops can have as much as 70% more myrcene than pellets of the same variety, but that difference is flipped when the wort is hopped as only 5% of myrcene is extracted from whole hops compared to 17% from pellets. This is why I prefer pellets for flameout and dryhop additions. Pellets also release more of their oils in a shorter time frame. However, I try to stick with leaf hops during the boil because their quality is typically better since it cannot be masked through processing like pellet hops.
In closing, you're really looking for the following:
*High hop oil content
*High myrcene
*Low levels of the other Noble hop compounds
*Long hop stand between 100-150 F
*Using pellet hops late
*Using a slow-working ice bath with a couple whirlpools
*Implementing a substantial dryhop in combo with long hop stand
