I've found the perfect book to use as a comp. It works because of the theme and the concept BUT I just dislike the writing (even though he has won several awards) and didn't find it to my taste at all. Should I still use it?
I know how hard it is to find effective comps. The only good thing about sniffing out good comps is that it requires you to read a lot of books. How we suffer for our diligence!
Comps aren't just about your book (theme and concept); comps are used to get an idea of the size and vitality of the audience for your book.
But you're not the audience for this Perfect Comp. You didn't like it.
How many other people felt the same way?
You have no way of knowing.
BUT every time I think I'm the only person in the world who didn't much like Very Popular Book, I'll see it mentioned on Twitter and a swarm of people confess to not liking it much, either.
One thing you can do is check the reviews on Amazon, particularly the ones with three and four stars. Here's where you find "oh hell, I was looking forward to this based on the reviews, and blech, what a disappointment."
The more of those you see, the less likely I'd be to use Perfect as a comp.
Here's the guideline: use books that you want to be compared to.