Well when you put it that way, "best place" is only as as good as saying "most convenient."

The best place you can solder to is the +5v point that is most easy for you to access. All of the +5v point are all of the same regulated source, so whatever is easiest. I feel like any other factors are nothing but trivial. As long as you keep away from the +6v battery contact or the -21v LCD supply, you should be golden.

I posted in a separate thread about my DMG overheating after installing a backlight and nobody said anything like that... it actually doesn't seem to overheat when it's plugged into an outlet rather than running on batteries.

I would still like to know the best place to solder for a backlight~

I used to have overheating power boards all the time. Then I replaced all the electrolytics in my gameboys and it's never happened again. They also sound more consistent.

http://store.kitsch-bent.com/product/capacitor-kits

In a different thread not too long ago, I think we concluded that an overheating power board is normal aging. I could be wrong. Someone please quote me on it.

So I can't wait for the nonfinite V5 backlight tutorial.

What is the best place to solder for this backlight or any other backlight?

I have mine soldered as you can see in the picture and the power regulator board is overheating...

Thanks! ^^