I am a huge fan of the Myst series. One of my first experiences in PC gaming was Myst. Now I haven't seen this asked. For those who have one or the other or both.
Which is most advantageous to buy? I might get both (and RIVEN).
I guess for the nostalgic, Myst ME and RIVEN would be the way to go. Then realMYST for something different. What are people's takes on this, what are some advantages and disadvantages?

Hi. Welcome to gog.
I'm a fan of the series myself and i have both Myst ME and RealMyst for a long time now (CD versions, and now the gog versions too). Sometimes i feel like playing Myst ME and sometimes i feel like playing RealMyst, as they're two different experiences even if the game is (mostly) the same. (RealMyst has an extra bit of content, Rime)
Given the extra content and the not so outdated visuals many people tend to prefer RealMyst, but any fan of the series will tell you you'll want both.
I think your plan of getting Myst ME and Riven, and then RealMyst later on is a sound one. Or, you know, get all 3 of them and case closed ;)
Anyway, here's the specifics regarding both versions (as i see it):
Myst ME
.movement is node based (some of us really like it like that ;) )
.higher quality stills (things kind of look more real, i don't know how else to explain it)
RealMyst
.an extra age that works as a kind of epilogue, Rime
.Realtime 3D
.higher screen resolutions and AA (i'm running it at 1920x1200 with AA and it looks great)
.dynamic weather system, day and night, etc. (water effects look great)
As always, i have them both installed and ready to go ;)

You know, you bring up valid points. And at $17.99 and an avid fan of Myst. There really is no point but to just get all three. Thanks!

First-person point-and-click.

#thanks.

If I'm a cheapskate who only wants one, which should I get?

realMyst, probably.

I agree, I have gog real myst & also masterpiece on cd & real myst is the winner here

It's kind of hard for me.
I now own both. realMYST is the BEST one. But going from realMYST to RIVEN is a hard sell. For the authentic experience, Myst ME to RIVEN is the best transition.

Dang it, I'm still torn ;-)
I'd get realMyst (this weeks 3€ promotion is what got me interested in the first place), but "Myst ME has higher quality stills" sounds compelling too. I'll take good looking stills over vague 3D any day. Argh. The choice. So hard! ;-)

Well, don't make your decision based on that one alone ;)
RealMyst looks very, very good, and having it looking gorgeous in fullscreen instead of a tiny viewport on a big monitor is also kind of a compelling argument ;)
In all honestly i have to say that for those who aren't (yet) fans of the series, and are considering to pick up just one of them, RealMyst is probably the way to go.
Fans of the series will definitely want to have both at some point.

RealMyst looks better than Masterpiece Edition, even standing still. The models and textures used in RealMyst are more detailed and beautiful than the ones that were used in pre-rendering the original game. Just look at the grass or stone in a couple of screenshots. The only real reason to go with Masterpiece would be either pure nostalgia or fear that RealMyst won't run well on your machine.