Oldest bike (2007-2015) That's still competitive and not dated

Winner! I rode a buddy's and he had RG3 build his suspension. It was the most stable 450 I had ever spun laps on. It left an impression I'll never forget. 

In my opinion at a local race you could win on any bike from those years…

You could go back to probably 1989 and not lose more than 5% on your lap time especially if you allow for basic set up, like bars, grips, suspension set up, tires etc.

Literally every bike made between 2007-2015 will get mentioned…

depends on the class, but i will tell you from personal experience watching it happen, i watched levi kilbarger smoke the A class for an entire year straight at the buckeye series in ohio on a 2014-2017 yamaha YZ450F..

I flipped a ton of bikes this year and i have vids of me riding almost every single one, 

i flipped: 2005 Crf250, 2007 Crf270, 2009 Crf250, 2015 Yamaha Y250F, 2014 Yz250F, 2011 Crf450R, 2017 Yamaha YZ450F, 2014 Ktm 250SX, 

rode: 2024 Kawasaki Kx450F, 2024 Yamaha Yz450F, 2022 Ktm 250SX, 2023 Gas Gas Mc450F, 2021 Yz450F, 2021 Gas Gas mc450, 22 Ktm 350SXF, 2022 Kx450F, 2016 ktm 250sxf, 2018 ktm 350sxf.

two that stood out of the bunch That i could have been competitive out of the bikes i flipped were:

2005 Honda CRF250R

Carillo long rod and cp 14.25:1 piston

This bike could be rode hard, and i mean hard AF and kept begging for more abuse, durable AF, the chassis was super complient, and handled lines like a fcking DREAM!!!!!

2014 KTM 250SX 

Hydrualic clutch, good linkage and swingarm design 

no counter balancer (some will argue, but its the best 250 2 stroke i have ridden!)

This bike is competitve cause bro the forks are so easily converted to KYB its not even funny, has so much power it will shit on any bike in the 250 class, and also is fast AF!!!! it comes with the good carb, good hubs, GREAT SHOCK (way better than this new garbage they are putting on the wp bikes) and it has the good throttle housing and cable, and great powervalve design, also extremely light weight.

This bike is my goto weapon, and i could hang right with any bike i mentioned above that i rode this year.

that 250 2stroke engine was so fast and hard hitting. and like you say i remember them as a really good bike just vibrated alot.

2007 Honda CRF 250R for me. Has an Athena Big Bore kit, Hot Rods Stage 1 Cam, Hot Rods Stroker Crank, Rocket Exhaust, etc.

To be honest. Those early 450's from 2004-2009 had a lot more power than some of them do today. But because they're carb'd the "mapping" wasn't as usable as they are today. So they were very aggressive with power delivery compared to today.