It's all a matter of opinion. As someone who has used both (these are the only two mechs I've used sadly, the Model M is my brothers) I can say they're both excellent keyboards, I personally prefer the cherry blues but that is because they are quite a bit lighter keys to press. They both give good tactile response (the buckling spring is technically superior in that regard IMO, just by how they work), and they both sound fantastic, though a little bit different (the cherry blues are a tad higher pitched, and give a plastic clack, the buckling springs are a tad deeper, and have a bit of a resonating ting sound as the spring vibrates back into place).
I recently acquired this MX Blue keyboard, to be honest as I had no real experience with the blues there was a bit of risk involved, risk which was somewhat alleviated due to researching the technologies, and the sounds, and what not. That said, what made me pick a cherry blue keyboard as opposed to a Buckling Spring keyboard (which was honestly what I was originally looking for) was things outside of the switch itself. Things like if I got a older Model M I'd lose the windows key (which is pretty important for me as OSX requires all 3), or the issue that if I picked up an older one I'd have to deal with an adapter, and if i picked up a newer one I'd not have all that great of rollover (I'm not quite positive if any M's have NKEY), stuff like that.
I like both switches though, prefer the blues a tad, but that's complete preference. The best bet is to actually see if you can't find the things to test. If you like clicky keyboards you've more then likely already dealt with a Model M, and know what to expect from those. May be worthwhile to find a cherry blue keyboard to feel a bit, if you have access to a good enough computer store (or friends that might have them), you might want to see if they have some of the razor black widows, those have the arrow keys exposed in the box so you can feel the keys click.
