I use a combination of d/l managers.. Mostly because, I need to leech out every last bit of available bandwidth out of my crappy internet connection (and
NO , to those who think they have a worse connection than mine..
YOU CAN'T POSSIBLY BE RIGHT). Here's the assorted goodies:
1) For Http/Ftp downloads, I've used both IDM and IDA, but they have their share of buggy moments. So its a tie . Although, before Flashget became the crap it is now after version upgrade from 1.81+, I used to be addicted to Flashget. These days, FG makes too many tcp/ip connection and jams up the router
2) For torrents, I use Flashget's (the new version, which doesn't have a great HTTP/FTP downloading capability BTW) inbuilt BT-downloader. For some strange reason, Flashget has become one of the best torrent downloaders I've ever used. Perhaps, because of its "PROTOCOL ENCRYPTION" option which prevents ISPs blocking your torrent connection to be fooled into believing that you're using a different protocol (other than Bit Torrent) when you're actually downloading a torrent file in reality

Although, meu-torrent has incorporated the same feature in its recent versions, but its still not as good as that of Flashget.
Finally a word or two extra props for Flashget (the old version, under that skin on the new one).
1) Its free, no more cracking, phreaking, browsing porn-infested crack sites for trojan-injected keygens etc.
2) The new interface is highly intuitive and ergonomic..with pretty/colourful buttons.
3) There are many options to organize, resume, save and edit your options/databases.
So had it not been for the especially bad experiences with recent versions of Flashget, it would've been my sole D/L manager

.