I like having a cheap digital metronome for when I'm travelling, or when I want to practice, and I don't want to have to go through the process of opening my DAW software just to get a click...also, at least for me, in Pro Tools LE, sometimes the click actually fucks up, it happens very rarely, but sometimes for 1 beat in a whole take, the click will be delayed or something...so I prefer to have a cheap, dedicated, hardware metronome for practice.
I'd say go to your nearest music store and ask them to show you all the metronomes that are in your price range. Thats what I did, and I got a very decent BOSS metronome thats digital, does different time signatures, has adjustable volume for different parts of the beat, etc.
If you want to do crazy time signature changes and such, you'll probably have to stick to a MIDI program or your DAW....its hard to find even high-end metronomes and drum machines that do that, and if they do, the interface is usually absolutely horrible.
