I like any quality wool felt pad. I currently have a Diamond Wool, 5-Star and several Impact Gels.
The Diamond Wool is the cheapest priced of the three, but quit serviceable. I don't really use it anymore though because I bought the Impact Gels and the 5-Star second hand from a friend.
I guess I like the 5-Star best because is is lightweight and has super-duper nice cushy felt. The Impact Gels are very nice too, but heavier because of the gel. I don't know if the gel itself makes much difference. I like them because of their quality felt. I would not hesitate to get another one though. I think they are cheaper than the 5-Stars and basically just as nice or nicer quality-wise.
I tell you what I like to do, which may or may not work well for you. But I buy a nice single layer Mayatex wool blanket and use that on the bottom under my saddle pad. Then when when it gets sweaty and crusty it is much easier to clean and dry than the thicker pads. So it encourages me to clean my blankets more often. I hate washing the thick pads. So after a handful of rides I will pull it off the horse sweaty, soak and rinse it in a tub of water, and hang over the tie-rail to dry. So my felt pads stay clean.
The reason I say it may or may not work for you is sometimes they will travel out from under the pad on long rides if you do a lot of hills. But it also depends on how your saddle fits. With one of my saddles it never moves at all. On my other saddle it will travel, but I normally can carry out a long ride without adjustments.