Quickclock is the best for me, I have jrummys app and its great but quickclock sets the clockspeed and voltages to what your particular proccessor can handle, you can set profiles as well.
1+ ... I've used all of them. While JRummy's "Droid Overclock" has the slickest and easiest interface, it uses preset values (at least for the time being...but I think he hinted adding some new features in future update). For at least now, I prefer to start with "QuickClock Advanced". Why? You can run it to test the lowest possible VSEL (voltage) that your Droid X can handle without crashing. After that it tests the highest clock speed that works on the phone, as well. Then based on what best works on your phone, you can select from among a couple options such as performance, battery saver, etc.
However, I don't really care for the QuickClock Advanced" interface. It looks like some antique MSDOS program. So what I do, is once it has defined the best presets (voltage and upper overclock speed), you can choose to export those presets. Then I open JRummy's Droid Overclock, import those presets, save them, choose the one I want to run ... getting the best of both.
Right now I'm running stock, rooted, debloated (freeze unwanted apps via Titanium Backup), and using the "Battery Saver" settings created by QuickClock. I've been getting 40-50 hours on my stock battery (the one that came with the phone...not an extended battery). The battery saver settings actually underclock my Droid X 300-900, but it runs more zippy than it did with any custom rom I used (ApeX, Liberty, Tranquility, etc, etc.) that I'm not really tempted to go back to a custom rom because even with the above settings I got only 1/2 to 1/3 the battery life I'm getting now.