To me, its six to one half dozen or the other.
That's it in a nutshell. It's a matter of personal preferance.
Both have their strong points, but they aren't game-changers. Equally well-made, performance will be pretty much identical.
Flemish will generally be quieter, especially on recurves. Endless are generally more consisitent from one string maker to the next. Endless settles in less, flemish is more adjustable. Etc. etc. etc.
Some find one easier to make than the other--not much difference to me. Either one takes some experience and good instruction to make properly.
If you like flemish, use flemish. If you like endless, use endless. You won't be missing out either way. 'Course you can experiment too.
FWIW, I have personal bows with flemish, and with endless, and I shoot them both.
Chad