This particular customer bought Cheviot, Merino, Corriedale and Norwegian wool tops for wet felting. The customer found Cheviot and Norwegian to take longer and feel more coarse than Merino.
All wool fibres will wet felt (as will some other animal fibres), but you will get different effects and will use different techniques depending on breed, staple, crimp etc, so there is no wrong or right answer to your question. As you say with the Cheviot and Norwegian you got a more coarse finish. This will be because they have a lower 'micron' than say Merino. This is information about the fineness of the fibre... Here's a guide I have written learning-the-technical-terms...
You will notice on my listing for fibres I list the micron count in most cases... if you want something close to a Merino in feel then you must select fibres that have a similar micron count. They are more likely to felt in a similar way and have the same fineness of hand feel. However, it should be remembered that each breed of sheep's fleece will have different characteristics when spun and felted (even at the same micron). So for example BFL (Blue Faced Leicester) is as fine as Merino, but is much longer and has a sheen.... so you can see there are many things to consider.
The best thing to do is experiment and find what you like that way... this is the only way to understand what you like to work with and what you don't. Every customer has a different opinion, so it is impossible for me to give you an exact list... as you work you will find what works well for you.
Sorry that's a bit vague, but this is such a huge and complex subject... the only other way to understand what you like and don't like, would be to sit with you and feel by hand each of your favourite pieces of felt and talk with you about why you like them, then I could suggest this or that.
I hope this helps?
You can find fibres at www.sarastexturecrafts.com
Have a wonderful day... Sara x