http://deskthority.net/wiki/Dell_AT101Black Alps on all the Windows key versions. Pink Alps on many of the previous versions. A few domes. The SGI Granite version (basically the same board) used damped cream Alps.
Not aware any ever came with blues at AT101 family is all tactile switches.
And yes, blue Alps are both really smooth
and really tactile as well. Unfortunately, the Alps heyday ended before Windows-key-based keyboards came into being, and the AT10*W boards are amongst the very few Alps CM boards with Windows keys or the standard Model M layout (though I read that the Model M copied a previous keyboard's layout). Decent Alps basically means nutter layouts.
Even then, the AT10*W keyboards have inferior scrapy switches. It's debatable whether the older tactile switches (e.g. pink) were better or not I briefly tried a vintage Apple board with what would be either pink or orange and that was really smooth, or so it seemed at the time. Should have bought it, then I'd have a comparison. Maybe Alps switches just wear smoother with use? My AT102W was NIB, after all and it sees very little use, just a spare board at work on the test/setup bench.
I am looking forwards to the Matias Quiet Pro when it ships to Europe next year (already pre-ordered). I want a nice quiet but tactile switch for work, but it will also tell me how nice a Matias switch would be if it was sold undamped, as tactile Alps switches have a great sound. My AT102W sounds a lot nicer than my MX brown Filco or my G80-3000 with clears.