Jesse - thought that's was what you meant, but wasn't sure since there are a lot of knots out there.:) Your observations about fraying with Mirage is a common fault with early generation floro (which Mirage is). Seagar's G-Max, Froghair, Rio, and Umpqua have reduced this "string cheese" phenomenon substantially and perform similarly (though I do have my preferences). Strangley enough, the fraying in floro doesn't weaken the materal as much as we would think. Nothing like it would nylon.
Jonathon - I don't believe there are "best knots" for everybody, but there are "best knots" for you. This is because everybody ties them a little differently. Consistency is the key and that comes through practice. That's why I wouldn't be too quick to change since you've been using your knots for years. Some materials will work better with the knots you use and tied your way so perhaps focus on materials first, especially if it turns out that you do have a bad spool or two?
A cool test is to take a one foot section of mono tied with different knots between two sections a couple of feet long (ex. a 4x section between two sections of 3x). Grab the outer sections and pull 'em until something gives. Do this a bunch of times, keeping track of which knot performs better for you. After a half dozen or so, a pattern starts to develop in most cases showing the clear winner. You may find the knots you always use will perform the best for you. BTW - you can also do the same thing with one piece between two flies to test knots for that purpose; or you can test materials this way as well. It won't tell you break strength, but it will show the strongest and most consistent material which is the more important anyway.
Louis -
Jonathon, try a triple surgeon's knot or a ligature knot to tie on your tippet. They are both stronger than a blood knot. A regular surgeon's knot can slip with fluoro.
For me, the triple doesn't perform well. It just doesn't draw up as nicely as the double. Slippage isn't the problem but easier breakage is. But again, that's me. Many like yourself find the opposite to be true. They're both examples of personal preference based on individual performance experiences.
Regards,
Kurt