I am currently using DR-05. Small, inexpensive and the quality is extremely good. The built-in mics are pretty good, but I use the line-inputs almost exclusively. You can record in WAV format or a variety of MP3 compression ratios. It records directly to micro-SD card. The one I have in there is 16 Gigs and it holds a LOT of songs in WAV format. It takes 2 AA batteries for power and battery life is excellent. I use rechargeable ones. It can also be powered by USB and that's what I generally use both on the job and in the car.
I also have a PR-10, that is even smaller and even less expensive. I also have 16-gig micro SD card in it. It works just fine, with fewer options and smaller built-in mics (which I don't use anyway). It is about 1" x 4" in size. I lost the battery cover from it, so I have clear tape over it, but it still is fully functional.
I previously had another model or two, plus a couple of Zooms. I prefer the Tascams, but all have been quite good.