My first impression is that you could hand me a board with any one of these switches and I would adapt and use it without complaint. Since there are options, here is my unscientific evaluation.
Foreword:
I'm used to Cherry MX Browns and recently acquired a board with Reds and modified it with O rings. If you are new to mechanical keyboards like I am and do the research before buying your first board, I'd venture to say that you probably came to the same conclusion and bought a board with Browns. After all, it is often touted as the best all-rounder. However, Browns actually turn out to be one of my least favorite switches on this board. More to follow.
A couple observations:
Once I start typing, I immediately notice that the grey switch in the spacebar is too heavy, causing me to mistype. I'm really enjoying the clicky keys but am a little wary of them with an infant sleeping in the next room.
Testing:
SensationComparing Linear (Red, Black);
This switch type feels very clean compared to the others. I'm still bottoming out even with Black since it's the only feedback I'm getting. Blacks feel sturdy when spamming the key but Reds modified with O rings provide a better experience. I quite like them for all-round use but remember, I'm bottoming out 75% of the time so I rely on that bounce at the end of the stroke.
Comparing Tactile (Brown, Clear, ErgoClear);
I barely notice the tactile feedback on the browns. While that is not a bad thing, it doesn't differentiate itself enough from linear reds. Think of the feedback on the browns as a little scratch or resistant spot while the clears produce more of a "pulse" sensation. ErgoClears feel a bit like Browns but obviously with a Clear pulse. The weight of the spring in the stock clears seems to lend itself to the experience and the ErgoClear to me, feels like it has lost that. I definitely prefer the Clears. (Wife assessment - "I prefer the ones in the bottom middle (ErgoClear)")
Comparing Clicky (Blue, Green, White);
Damn I love that click but it's hard to justify the noise level. Audible feedback combined with tactile response greatly helps me bottom out less. If I could muffle the sound a bit, there would be harmony. Perhaps soft landing pads (as mentioned by CaptainBadass in his review) would help with the accoustics. This is not really a switch type for O rings. Stock Blues and Blues with Clear spring are my favorite in this category due to the weight. (Wife assessment - "They feel like I'm typing with long nails")
WeightThe 45g spring in Reds and Browns may be a tad light for me but still quite usable. Moving on to Blue (rated at 50g), spring weight feels the same but the tactile and audible feedback reduce bottoming out.
55g Clears feel great and are where I would stop. In what is obviously an illusion, I found it odd that stock Clears feel like they take less force than the same spring in a Red or Black switch. Perhaps due to me pressing the linear switches all the way down and half way in the tactile. I also like the Clear spring in the Blue and White switches.
60g in the Black feels a little heavy. I wouldn't want to spend too much time typing on these.
80g in Greens, Grays, Whites etc. are just too heavy. I miss keystrokes all over the place.
Conclusion:
Each switch presents its own ideals and its own target audience, so knowing what I do now which would I buy?. My taste seems to be very middling so I present you a list of switches in the order of my personal preference:
1 - Clear
2 - Blue or white with Clear spring
3 - Red (modified with O rings), Blue
3 - ErgoClear
4 - Brown (stock or Clear spring)
No Want - Black, White, Green, Gray, rest of heavies...
Using the Universal Switch Tester has been a very enlightening experience and I'm glad I had a chance to be a part of the tour. Thank you Hashbaz for making it available!