For me there would be no question, the KX250, but I weigh quite a bit more than you. With the CR125, you will have to keep it on the pipe and be aggresive to have power, so I believe the 250 would make a much better trail bike, as you can still lug it, especially bored to 265. This is taking for granted that they are both in the same condition. Now which is a better deal is another matter as your comparing 3 years difference model years. You've owned 3 dirtbikes in 1 year?
Good luck with your decision.
John