I want to get one of the 3 Unreal Tournament games offered on GOG.com and I need help deciding which. I've played all 3 but not recently enough to remember how good they were. Just looking for suggestions, thanks.

There is only 2 of the Unreal Tournament games on GOG the other 2 games are just the unreal games. Out of the Unreal Tournament games I would go with 2004 first as its the most accessible online, has more modes and a ton of great mods. If you still want another deathmatch game after then UT99 is also worth grabbing just for the great assualt maps.

I'm pretty sure there are three unreal tournaments on GOG. There's Unreal 2: The Awakening SE (doesn't have UT in the title, but it still has multiplayer), Unreal Tournament 2004 ECE, and Unreal Tournament GOTY (is this the one you mean by UT99?). I was trying to decide between 2004 and UT Game of the Year; I'm just thinking of how much I liked the vehicles that were in 2004.

Unreal 2 is the sequel to Unreal Gold, It may have multiplayer but its not really in the tournament series. That said I haven't played either Unreal gold or Unreal 2 so can't comment on those. Also yea I did mean Unreal Tournament GOTY when I said UT99. 2004 Has vehicles as well as a few other modes the first game doesn't have. To be honest they are both great games and both worth playing in their own respects but 2004 just has more for the money.

Unreal 2 doesn't have multiplayer out of the box. You have to download a separate add-on.

If you're going to count Unreal 2 as an Unreal Tournament game because it has multiplayer, then why not Unreal as well?
Anyway, Both UT games are good and loved by many, so I suppose the best thing to do would be to check out some gameplay videos and decide which one seems more interesting to you.
I personally prefer the first one because it plays more like Unreal, and I'm not a fan of having to spend more time in the air than on the ground as you do in UT04.

Get UT2004 if you're into multiplayer gaming. About 800 servers up.
Don't think of getting UT3 since it was a fail and not really popular these days.
UT99 is kind of too old but you might consider that too. It has worse GFX and gameplay is slower than UT2004's, but depends what you want.
Unreal and Unreal 2 aren't really worth playing if you want multiplayer, but you might give them a try if you want some story.

Just get both Tournament games and Unreal Gold.
I like UT99 a little better than UT2004 because it runs much smoother on my laptop and has better music. But both games are awesome and play somewhat differently from each other.
Unreal Gold I highly recommend just because that's what started the series and is a great single player game, and it has a decent multiplayer mode as well.

Personally id say UT99.. I enjoy it a lot more than the newer UTs.
But again thats my personal preference.

Unreal GOTY is best

UT99 is by far the fastest gameplay, ut2004 is too slow, and without ons it would be fail.

u can't even dodge much in ut99.
So get UT2004. It also has most community-made content. And you can always find something interesting in ut2004 to play - be it regular deathmatch, assault, trials, racing, zombie horror, sniping, freezetag.. whatever. UT2004 has it all.

The only one that I know that I'm missing is Unreal 3.And GOG doesn't have that one yet. But, I'm hoping they get it SOON! so I can add it to my collection. Everyone wants something different so, if you're looking for the fastest & most modded game that GOG has then I'd buy Unreal 2004 ECE. It's well worth every coin you spend.