For the ultimate in field recording versatility, the Tascam DR-40 is a great one. This handheld, 4-track field recorder has flexible I/O and onboard phantom power and will last you fifteen hours with three AA batteries. If you want to edit something on the go, the DR-40 has you covered with onboard effects such as reverb and EQ. The condenser mics in the DR-40 can be manipulated into XY or AB configurations for tons of control over your field recordings.