Having moved from java to ruby, I am struggling to find a good IDE for ruby. I used eclipse on java, so I tried Aptana Studio (previously Radrails), but its not even half as good. Currently I am trying out Netbeans for Ruby. Please suggest me the best RoR IDE out there.
I believe TextMate is universally accepted as the best editor on Mac OS X. I am looking for windows. So far it seems netbeans and e-texteditor are worth a try.
Emacs with emacs-rails package. TextMate has less steep learning-curve if you run OS X, and is really popular among Ruby/Rails developers. Maybe you should try NetBeans as well, it's probably the closest to your earlier experience with Eclipse.
Which OS? Textmate is the standard on OS X. I've tried Radrails and others, but in the end I prefer the lean editors for Ruby. I'd probably use vim on Linux.
If you're willing to shell out for Visual Studio this may be worth considering. I tried it a couple of years ago(ish). Was quite good.
If you are stuck on Windows, then I've found Aptana to be pretty much the best of a bad bunch so far. If you can get a Windows TextMate clone you are happy with then that can substitute as a RoR IDE as well.
If you are (or want to start) using a Mac, then TextMate is your best bet :)
Netbeans! Especially the 6.5beta or development version.
I've been learning Ruby using it for a week (or 2) now. Since I wasn't able to either make rspec tests using Eclipse/Aptana and Netbeans did it from scratch - that's one of things that made my choice.
Also "Netbeans TV" has lots of screencasts that can help you understand features. Great code completion and full support for TextMate templates.
I found netbeans ruby package quite good. Thought it is quite big and memory expensive than others.
Usually comes down to personal oppinion so try out and decide what is best for you
EDIT: A good Textmate clone for windows is E-Texteditor
While not an IDE, if you're on OS X, textmate is beautiful. On windows, you can try e-editor.
Windows
E Editor
Linux
vi(m) (recommend using the rails.vim package here) emacs
Mac OS X
TextMate, great bundle support for not only Rails, but HAML, RSpec and a whole slew of other things too.
Take a look at Aptana Studio. It is a pretty nice ide and has a free community version. I use it for all my PHP and HTML needs.
Java IDE: Aptana Studio
Mac: Panic's Coda (my personal favorite) and Macromate's TextMate
Windows: E Text Editor (my personal favorite when on Windows)
I like Netbeans 6.5 but I have to admit it is pig slow even on a fast machine.
What? No-one has suggested vim yet?
It's got great rails support - the rails + project + taglist plugins give you much all the standard ide behaviour that you need.
It's fast, light on the memory, and pretty much completely consistent across all platforms...
latest netbeans is awesome for rails development, autocompletion and inline documentation really works, the only thing i'm missing is haml/sass support
I don't know if it will convince me to stop using Textmate but I came across RubyMine from JetBrains today and am gonna give it a shot.
It may not have the most extensive feature list but I love the simplicity of Komodo Edit (if you can't use Textmate that is).
I try to stay away from full IDE's and lean more towards text editors. IDE's just tend to be very bloated and do more than I want them to do. When I first learned to program (in java) I used several IDE's - mostly eclipse. Later when I tried writing programs without it I realized what a huge crutch it had been, I couldn't even write code without it - I couldn't compile, my code was riddled with errors because I didn't have the syntax checker, etc. In my (perhaps limited) experience I've foudn that with any language/platform just a text editor really helps me get down nitty gritty with it. I feel like my learning rate has increased 10fold and I feel much more in control. Rails is no exception.
Windows - Notepad ++ (free, open source). Just an awesome text editor. I use this at work.
Mac - I am a poor student and I never regret the 50 dollars I dropped on TextMate. I use it for all my classes - and I use it for developing in rails, of course. :) Nothing quite like it. Pretty much everyone compares other text editors to it as a standard.
Everything - vi(m). What more can you say?
I don't see a reason that Vim is recommended only on Linux; it looks and performs equally well on any modern platform, uses native controls, fonts, etc.
If I were on Windows I'd check out Cream - a "modern configuration of vim", as it's labeled.
Intype it's an awesome editor, fast and pretty ... try it and see !