I've tied my own leaders almost as long as I've been fly-fishing. At first I did so because I enjoyed the hands-on connection with all aspects of my tackle, and to a lesser extent because I could tie a leader for a fraction of what a store-bought leader cost. As my casting skills improved, I found I could adjust my hand-tied leaders to suit my personal casting style and tweak them to fine-tune my presentations, both with dry flies as well as nymphs and wet flies.
I've simply never found a knotless tapered leader that performs even close to as well as a properly crafted hand-tied tapered leader does. I think that is partly because knotless leaders are made from material that is softer and limper for a given diameter than the comparable level leader material we buy on spools for tippet material or for tying leaders from scratch. That characteristic can be desirable for some situations or casting styles and not so much for others.
The one characteristic of any leader that most defines its performance, however, is its taper. Years ago, I measured the diameters of several brands and types of knotless tapered leaders and found the majority of them were mostly a straight taper or nearly so from butt to tippet. Again, this characteristic can be desirable for some situations or casting styles and not so much for others. I'm not sure if this is still the case with most of the current brands of knotless leaders, but I believe it certainly is for some. Overall, I have always found a straight tapered leader more troublesome to cast and to fish, and I much prefer a compound tapered leader.
When I first decided to tie my own leaders more than 40 years ago, I bought a leader tying kit from Orvis. Along with a dozen or so spools of leader material in various diameters, the kit included a brochure with the all-important specs for leaders of various lengths and applications. Most of the basic trout leaders were designed around a compound taper that used what I like to call the 60-20-20 ratio: a 60 percent butt section, a 20 percent transition section and a 20 percent tippet section. The leaders I tied based on those Orvis recipes worked well for me then, and most of the leaders I currently use are largely built around the same specs, with the occasional tweak here and there.
In spite of the superior performance of hand-tied tapered fly leaders, virtually no fly tackle suppliers offer them anymore. One exception is Flyfisher's Paradise in State College, which still offers hand-tied leaders made in the United States at great prices. And for those who would like to start ting their own leaders, leader tying kits getting hard to find. Even Orvis no longer offers a leader tying kit, although Flyfisher's still has those as well.
Fortunately, most fly anglers probably already have an assortment of their favorite tippet material in various sizes from 2X down to 5X. To tie some complete trout leaders, you will just need some heavier material for the butt and transition sections measuring .019 (inch), .017, .015 and .013 in diameter. I like Maxima Ultragreen for my butt sections and Orvis Super Strong for my transition and tippet sections, but feel free to use whatever brands you may prefer.
My basic 71/2-foot trout leader is simple and what I use as a foundation for most other leader lengths I might need. I start with 18 inches of .017 and .015, then 12 inches of .013, followed by 6 inches each of .011, .009 (2X) and .008 (3X). To this basic leader, I can add a 24-inch tippet section in my choice of either 3X, 4X or 5X. For a 9-foot or longer leader, add a length of .019 to the butt section to extend the leader to the desired overall length. Maxima isn't available in .019 so use it in .020. Use a blood knot or surgeon's knot to join the individual sections of leader material together.
Once you start tying and fishing your own leaders, you will develop a better understanding and feel for leader design. This will allow you to shorten or lengthen individual sections of your leader to make it perform better. Generally, I prefer leaders with longer and stiffer butt sections for nymph fishing, especially early in the season when I'll be using extra split shot to get the flies down. For dry flies, I like leaders with longer transition and tippet sections that make it easier to throw slack or curves to achieve a drag-free drift. Once you get a leader performing as you want it to, be sure to record the specs on a card and keep them with your leader tying material so you will be able to tie more when you need them.