for me free download manager is best.
i used getright dap, ida, idm and ... but FDM(free download manager) is the best.
it support zip file preview and query size option
download it from: www.freedownloadmanager.org/download.htm

The best download software I’ve used is BitTorent and other versions of it. I like it because you can find pretty much everything you might think of; from movies to TV series to any music and animes. Also if enough people are either seeding it or downloading it, it is extremely fast. I’ve downloaded 40 min of video in less than 20 minutes.

BitTorrent can't actually be considered a download manager, since it can only be used for downloading torrents - therefore it's a peer-to-peer software. A download manager is something that allows you to download files from servers.

Until a year ago, I used to use Star Downloader, as it satisfied me the most. However, some time after switching to Firefox, i realized that no download manager was necessary anymore. They are useful only for bigger files, and I do not download such things. So I use the in-built Firefox download manager.

I see I see. I guess I've not really used any download managers then. Where might they be useful?

Most of them say that your download speed will increase. This is nonsense - it might increase for a few bytes, but that's too small to be noticed. Another function that actually proved to be useful is the ability to pause downloads. Sure, Firefox also has this option, but most of the time it hasn't worked for me - and it can be useful when downloading pretty big files.

I use torrents to download my files. uTorrent, very fast and easy to use. Get what you need all the time!

but why you dont use bittorrent ?
it is a full program and free for all

You use bittorrent client in order to download from bittorrent servers.
If the thing you want to download is not on a bittorrent server, you cannot download it.
For instance if you want to upgrade your phpbb forum to the latest level, or if you want to create your phpbb forum from scratch, you donload the distro from http://www.phpbb.com/downloads.php ,
which is a http server, and not a bittorrent server.
In other words,
- you use a ftp client in order to download from a ftp server.
- you use a http client (IE6 or Fireforx) to download from a http server.
- you use a bittorrent client in order to download from a bittorrent server.

And you use myveryprivate client in order to download from myveryprivate server...

I would just like to add that most of the browsers and download managers can download both from FTP and HTTP servers. That is, of course, if the FTP server is public - no username or password used. I can't guarantee that you can use a browser/download manager for downloading files from "protected" FTP servers. Whereas you might be able to enter them through a browser, I presume you would need a FTP client to download anything.

I used dap, fresh download manager, Accelerator, D4X and much more, but the best always was Gozilla for windows and D4X for Linux, and i'm on the other side from what pysot said, it really increases download speed, ofcourse it doen't touch internet speed, but it uses every byte in your connection to accelerate your downloading speed, so you can notice not less than 12kb diffirence in speed when you use it on 512kbps ADSL for example "the connection i use", also it can pause and resume and this so much helpful in huge files downloading.