I will preface by noting that these are my opinions.
Your opinions may and will differ.
The YZ250 has been one of the most versatile and reliable motorcycles available for many years. I can really do anything with it.
For an off-road platform, the biggest drawback is the super tall 1st gear of the YZ 250 and the absence of an E-Start. This is where Euro bikes shine, they have the magic start button and once they get going, they pull and lug at snail speeds due to their granny gear for 1st. 1st on a YZ is almost like 2nd on some of the Euro bikes.
Until I ride a Euro bike that makes me smile as hard as the Blu Machine, I will continue to be at a disadvantage.