Hold-out missions, i.e. maps where you have to defend for X minutes, are pretty much one of the more "standard" types of maps and it's likely that you will encounter at least one map of that type in most classic-style campaigns. I don't recall any campaign that would use this kind of mission particularly often, though.
As for good campaigns, I'd recommend using this:
Maps | HIVE
It's the map repository with enabled "campaign" filter and sorted by user rating. You can find filters to the right of the page and you can sort the results by your desired field by clicking on the bar just above the first displayed map.
For my personal favourites and generally highly rated campaigns that resemble the original W3 style, I'd suggest:
a) Campaigns by
@tomoraider
Rise of the Blood Elves v3.0
Curse of the Forsaken v3.0
b) Campaigns by
@Shar Dundred
Legends of Arkain First Undead Book
Legends of Arkain First Orc Book
Legends of Arkain First Human Book
Second Human Book of Arkain
c) Campaigns by
@Turnro
The Adventures of Rowan the Wise v4.4
Resurrection of the Scourge
Jeopardy of the Horde
Malfurion's Quest v1.3b
d) Shadows of Hatred by
@Sclammerz
Shadows of Hatred v1.4
BUT! These are only a couple of examples of great campaigns available here at the Hive. Personally, I'd recommend that you simply go to the Maps repository and try any campaign that you think sounds fun - I'm pretty sure that sooner or later you will find a project that you enjoy
Just a little warning, be sure to check the recommended game version for each campaign before you try to load it up. Recent patches to Warcraft 3 have caused some compatibility issues and certain campaigns might not work if you do not have the appropriate game version.
Also, if these are not enough, you can also go and check here:
Map Development
This is the Map Development forum. This is where people discuss projects that are still work-in-progress - a lot of them offer playable demos, so if you don't mind sinking your teeth in an incomplete project, you might also find a lot of cool stuff there.
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As for patch levels, as
@Daffa the Mage said, for older maps, 1.27b will likely be the safest bet. For others, you might have to patch your game to at least 1.29 or to the newest version, the latter can be done by simply trying to connect to the battle.net from within the game.
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And finally, you're always welcome to try and work on your own project! The editor might be a bit scary at first, but the truth is that it's not that hard to get a hang of things. If you wish to go down this route, I'd highly recommend checking out the Tutorial forum for guides and tips
WarCraft III Tutorials
And if you happen to have any questions about map-making issues, you are always welcome to ask them here:
World Editor Help Zone
Triggers & Scripts
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Whichever one you pick, I hope you find a lot of fun on the Hive
