I forgot to pack my Tascam DR-40 for my trip and ended up getting a Zoom H4n Pro. Both are good recording devices, but overall I prefer the Tascam DR-40. Here's why:

1. The DR-40 can be powered by USB. This means if I run out of batteries, I can always plug it into a computer or power outlet. H4n Pro cannot do that.
2. DR-40 can record a backup at lower volume. Insurance for when (not if) your main track clips.
3. DR-40's controls are more intuitive. Most functions used on regular basis have dedicated buttons are are two clicks away. Zoom mostly relies on menus navigated using a wheel and click mechanism. For example, to enable or disable phantom power is a dedicated button on DR-40, while it's H4n Pro has to be changed in the menu.

I haven't checked the audio quality, but I expect both to be adequate for my use. The DR-40 is cheaper, and better thought out controls. You should get it if you need a digital recorder.