When comparing Textastic vs Coda 2, the Slant community recommends Textastic for most people. In the question“What are the best programming text editors for the iPad?” Textastic is ranked 2nd while Coda 2 is ranked 3rd.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro iOS version available
Pro Supports 80 source code and markup languages
Textastic has support for several script and markup languages.
Pro Very fast
There's no need for hundreds of modules to be loaded on every start of Textastic. It's perfect for the fast editing of files.
Pro Supports online sync
Textastic can sync with iCloud documents.
Pro Code completion
Pro Real IDE with all the benefits
Coda 2 comprises all you would expect from an IDE: it supports multiple languages (including all the standards); it performs autocomplete of project names, as well as language functions; it supports SVN and GIT; it has good support for plugins (or you can write your own); it has a configurable editor; and it has a built-in preview.
Cons
Con Mac only
Textastic is for Mac only.
Con Proprietary
Textastic is a proprietary software and needs a license which costs $7.99.
Con Defective UI
There are several things in Coda that simply don't work, and never have. For instance, the root directory for your local and remote files is simply not honored. For every project, you can specify the root directory for its files. But when you open the project in Coda, it doesn't go there. The file browser just shows whatever the last directory was that you were using, and will write files to the wrong place. Thus, it defeats the purpose of setting the home directory in the first place.
Also, splitting the editor doesn't work. If you've done any programming, you know how important it is to be able to view two files simultaneously. Coda fails to do this, with a bizarre insistence on making the two panes dependent on each other.
Con Support for Mac and commercial use only
Coda 2 is only available on Mac (even though that does make it a native app, meaning its much faster). Coda 2 costs $99 after the 30 day free trial is up.
Con No XDebug
If you also write PHP, there's no XDebug support available.