I'm looking at taking a road trip to OKC in late February/early march. I'll be coming from Pueblo, Colorado, and there are several routes I can take. Here are the two that I'm considering the most:

I-25 to Raton, NM; US 87/287 to Amarillo; I-40 to OKC

US 50 to Lamar, CO; US 287 to Amarillo; I-40 to OKC

Which one would you suggest? Any other suggestions?

I usually take I-70/I35 but have had to adjust to an I-25 route because of I-70 being closed from Watkins Road east to the Kansas border because of snow. When I went to Raton I just took the road through the panhandle to the Northwest Passage (State Hwy 3) into OKC. I have also taken I-25 to the Springs, east to Limon and south into Oklahoma then the Northwest Passage into OKC.

Of your two I would take the Raton/Amarillo Route.

Now, if it is a light winter by then, and if you like scenery, here's a different suggestion.

I-25 South through Raton and on to Springer, NM
East on US 56/412 to the NM State Hwy 39 T intersection.
South on NM State 39 to and through Logan NM (I love this stretch when it is clear weather; would not touch it in ice/snow weather
SW on US 54 a few miles to NM State 469
South on NM State 469 to I-40
East on I-40 to OKC (or at Sayre, Hop onto OK State 152 and then OK State 37 and two lane your way east until you hit I-44 just south of OKC

Yeah I usually take the first option through Raton as well. It's faster and more scenic.

I'd do Raton, down through Dalhart , Amarillo then I-40 as you mentioned.

We ski in Vail every year and have taken all of the routes. What we've found is that the I-70 to Salina and then south on I-35, while longer distance wise, takes no longer in terms of time, and the entire route is divided highway. We feel it's safer. I've seen them all closed because of snow or icy conditions, but we've never actually had to interrupt our trip.

That's the route my SiL and his poppa took last weekend, although they were doing it the OKCS-Denver direction. They hauled a van and a third(ish) worth of items toward Denver, where they picked up my daughter and Poppa's world's bestest grandbabies, and then they went to their new home base in WY. He said it was a smooth drive, rather dull, but smooth.
In iffy weather, I'd definitely consider the main byways like 35 and 70. With clear ground and skies though, I'm rather happy cruising the two lanes.

The problem is in iffy winter weather I-70 tends to get closed on the eastern plains. The divide weakens the storms over the Front Range and the storms strengthen after leaving the Denver Valley. Yeah it's a bit more boring but taken enough times even the small town route gets boring. I'm usually splitting the driving with someone and it is just simpler to point someone else in a general direction on the interstate and set the cruise control. When we have driven up there from Austin (usually hauling the motorcycle up to ride in the mountains) we have made it a two day drive stopping and seeing my family in OKC. The last two times we have flown with the cheap Frontier flights and not done the Austin to Denver drive directly.

We ski in Vail every year and have taken all of the routes. What we've found is that the I-70 to Salina and then south on I-35, while longer distance wise, takes no longer in terms of time, and the entire route is divided highway. We feel it's safer. I've seen them all closed because of snow or icy conditions, but we've never actually had to interrupt our trip.

no doubt this is the best route to denver/vail .... but from pueblo the raton/amarillo route is the fastest by a good bit

They just need to build an interstate from OKC to Denver and make it easy :)

There is a KS state highway off of I-70 right before The I-35 Salina exit that spurs onto hwy 96 thru Hutch then down to WHC(I-235 loop)then curves back onto The Turnpike(I-35)!I dont know if it's any quicker but a change in scenery is always a good thing if time alows!