What are your main projects going to be? TV commercials? Motion graphics? Long form or feature-length film? Training videos? News?
I love my Adobe suite because it does what I need it to do, the different programs work very well with each other, and its easy to use. I do quite a bit with TV commercials, 3D animation/3ds max, and motion graphics, so I find Premiere Pro and After Effects to be my killer combo. I think Photoshop is an indispensable tool that every editor should have just because it can save your neck in a pinch if you have to clean up a logo or touch up a photo or still frame. Adobe's Media Encoder and Encore programs are simple and straightforward, so you can output to all kinds of compressed files or DVDs, respectively. If you're doing things in HD, Adobe supports Blu-Ray authoring. I don't care too much for Soundbooth, but from what I hear, the CS4 version should be better.
I also use Final Cut Studio 2 at the office. Personally, I'm beginning to enjoy editing long form material with it, but I can't stand trying to do simple things with text in Final Cut. So while I like it for big projects like feature-length films, I don't like it for small TV commercials and other simple stuff. In some ways, its similar to Premiere Pro, but the keyboard shortcuts are just different enough to make you want to pull out your hair until you get used to it. Also, I find that Compressor can be a very finicky and non-intuitive program. I've had several renders fail, and it never gives me a reason. If there's one thing I can't stand, its when something isn't working and I get no clues as to why its not working. All that aside though, if you're more familiar with Macs, you might be more comfortable with Final Cut Studio. It's less expensive than Adobe's Suite, but if you end up buying Photoshop to go along with it, the prices will equalize. If you're doing things in HD though, Final Cut Studio does NOT support Blu-Ray authoring. They might start supporting it in the next version, but I think it's still under debate. There are several people here that really like using Final Cut, so if you're looking for more positive reviews, people like Alaska CameraDude and AlexLucas might be able to chime in. They both have a lot more experience with FCP than I do as well, so they can probably offer a few tips and things if you go that way.
As for Avid, I don't have much experience at all with it. I hear its an industry standard, but frankly, I didn't even know of its existence until I had been working in video production for more than a year! A lot of people swear by it and say its the only way to go for video editing. Me? I downloaded a copy of Media Composer to try and learn it, but the program makes no sense to me. Things in FCP and Premiere that take one click of the mouse take multiple clicks or hotkeys combined with mouse clicks in Avid. I find the whole interface counter-intuitive and incredibly confusing. Also, Avid is the most finicky and selective when it comes to running on your computer. You need to make sure that your machine meets Avid's SPECIFIC requirements, or you'll run into problems. Also, I think its the most expensive option out of the three, with its Media Composer package running around $2500. Last I heard though, Avid was making changes to its software lineup and was going to discontinue one or two titles while bringing its Media Composer title down into more of a mainstream price bracket. I think if you're familiar and comfortable with Avid more than the previous packages, it would be a fine choice for you. I know Grip here knows his way around Avid, so he might be able to describe its attributes better than I can.
Hope this helps, and good luck!