Your advice was so valuable because it went far beyond the cookie-cutter tips typical of coffee chats or quick phone calls.
1 a: CUSTOM-MADE // bespoke suit
I would argue that bespoke has the connotation of being particularly fancy, which draws a nice contrast to boilerplate or cookie-cutter.
I'm not sure if it's quite ideal for your situation, but here's how you could incorporate it:
Your bespoke advice was so valuable because it went far beyond the cookie-cutter tips typical of coffee chats or quick phone calls.
Another option that works for this particular context is singular:
3: being out of the ordinary : UNUSUAL
Possible ways singular could be incorporated:
Your singular advice was so valuable because it went far beyond the cookie-cutter tips typical of coffee chats or quick phone calls.
Your advice was singularly valuable because it went far beyond the cookie-cutter tips typical of coffee chats or quick phone calls.
(adj) 2a. restricted to a particular individual, situation, relation, or effect
(adj) 3. free from ambiguity
Which can be used in various ways, to show why you appreciated that advice:
Thank you for giving me such specific advice.
Meaning; thank you for giving me advice, that was directed at my individual situation, and for me personally.
I really appreciate your advice and how you give me specific solutions.
As in; thank you for not just giving me generalizations; but giving me unambiguous steps to follow that I can use to solve my problem.
Your custom advice was valuable because it addressed my particular needs.
made to the specifications of an individual customer
This sense of custom can also describe something that is made just the way you want it.
: characterized by careful reasoned thinking
e.g. a thoughtful essay
: matured by extended deliberative thought
e.g. a considered opinion
Edit: All my suggestions have some non-zero history of usage.
from tailor (v):
- make (clothes) to fit individual customers
- make or adapt for a particular purpose or person
targeted is also fitting here
My first thought after reading the title was "bespoke."
But I think context matters and bespoke may not be the best word to use for your example.
Bespoke connotes tailored clothes. The opposite of bespoke is "ready to wear." I've also seen bespoke used for other products beside clothes, but the usage seems to be about things hand made.
You example context is different. It's about communication. Written communication in the case of boilerplate.
I can send a boilerplate email, but for the opposite, sending a bespoke email doesn't seem like the right usage.
Maybe for personal communication the opposite of boilerplate is... personalized. The communication is specific to the person. "Thank you for your personalized advice. It was much more helpful that the boilerplate answer on the website FAQ."
I'd probably use unconventional here.
Cookie cutter means adhering to the norm. I don't know that I'd typically describe advice that way, but that's the term you requested a semantic opposite. I'd personally use the term conventional like in conventional wisdom.
Thank you for your unconventional advice! It was much more helpful than the run-of-the-mill conventional wisdom I got from everyone else.
Outside the box also has currency here. It means that the thought process in question was unconventional or from a new perspective.
Thank you for your outside the box perspective. It was far more helpful than the conventional advice I received elsewhere!
1 Able to be used for a practical purpose or in several ways.
‘aspirins are useful for headaches’
1.1 British informal Very able or competent in a particular area.
‘He is a healthy sceptic to much paranormal activity, and would be a useful expert to have.’
Used in your original sentence:
Your advice was so useful because it went far beyond the cookie-cutter tips typical of coffee chats or quick phone calls.