When you miss a putt, you had one of three things wrong. You missed on the speed, you missed on the line, or you did everything else right and you had your putter aimed wrong.
The line and speed will always be dependant upon you the golfer and the individual putt. they must be selected at the time and place the putt is happening.
On the other hand, you can help to guard against the third possibility by getting yourself a putter that is easy to align.
I have a semi mallet type of putter with three very distinguishable lines across the top. As a convenient insurance policy, I also make the line on my golf ball the same length as the lines on the putter.
There is not that speed is king and line comes in a very close second. But neither is achievable or relevant is you don't get the putter lined up right to start with.
Putting is hard enough because you are trying to roll the ball down a line that cannot really be seen. Your putter should help you to make that line as clear in your mind as possible.
You should have to guess about how your putter is lined up. The marks should jump out at you and be unmistakable. Only then do you have a proper reference for the line your putter intends to start the ball on.
Hopefully, it is the same line that you have read the putt to be.
Instead of going to a long putter, get one that is easy for you to line up on a day in and day out basis. That, or you can keep on guessing with your old putter that is causing the alignment problem to begin with.
Let me show you how to start every putt on line.