When comparing Colloquy vs Linkinus 2, the Slant community recommends Colloquy for most people. In the question“What are the best IRC clients for Mac?” Colloquy is ranked 3rd while Linkinus 2 is ranked 6th.
Ranked in these QuestionsQuestion Ranking
Pro Free and Open Source
Pro Nice Native Design
Colloquy was designed with the Mac OSX interface conventions in mind, so it's got a native look and feel.
Pro Has pretty themes like iOS "bubbles"
Pro Works on macOS Mojave
Although not supported anymore, it's been confirmed to work on Mojave.
Pro Plenty of advanced features
Colloquy has many of the features an advanced user would need, such as file transfer support, and even support for mIRC colors. It supports scripting via AppleScript.
Pro Supports SILC and ICB
Pro Mobile version
Colloquy also has an iPhone version for IRC on the go with many of the same features.
Pro Searchable logs
Linkinus 2 lets you search chat logs by keyword within the app. You can also enable or disable logging on a per-channel basis.
Pro An extensive feature set
For those looking for a feature packed client, Linkinus 2 is for you. The $8 USD price point is almost justifiable by the feature list. It frovides features not seen in other IRC clients such as embedded media(Youtube, Vimeo, etc.) and can automatically expand shortened URLs.
Pro Major improvements over first version
With the new version release, Linkinus 2 is up to 10 times faster. It also has new core features such as auto reconnect, proxy support and much more.
Con No longer supported
The app will not work on the latest releases of OSX as it has not been updated since 2014.
Con No way to search chat logs within Colloquy
Chat logs are not viewable within the app. You must go to the directory and open the file with a text editor.
Con More expensive than most IRC clients
At $7.99 USD on the App Store, Linkinus 2 is more expensive than most IRC clients. While the extensive features may justify the price for some, basic users probably do not need to pay for a commercial client.
Con No Notification Center support.
Linkinus 2 does not support OSX's Notification Center meaning you'll have to keep an eye on the window as you won't be getting alerts straight to your desktop.