which bike should I get?

Hi I am looking to buy a used rm 125 two stroke or a rmz 250 four stroke I like the looks of both bikes but would like to know which one has more power and will last me longer power wise I have quite a bit of experience and bike weight in the air does not scare me which means it comes down to power, performance, and which one will scare me the best when taking corners or riding fast. I would like to hear from a rider who has experience on both bikes and is very serious about the sport. thanks

My 16yrs. old son and I both have 2005 YZ125 and CRF250. I think there is much value riding the 125 for a few years and picking up additional skills prior to jumping to the 250F. He absolutely loves the YZ125 and I don't think he would even consider 250F until he weighs more & needs extra power.
http://www.motocross-dirtbikes-atvs-guide.com

well i ride a 2003 rm125 but it does have more power than stock as it has been raced, but i can leave and 250f standing and even some 250 450fs can only just keep up, and after riding a friends 250f i am definatly set on riding 2stroke for now due to the rm being so light but so much top end power for a 125