These units can all be used hand-held to detect and record bats.
The Anabat Walkabout, Pettersson M500, M500-384, U256 & U384 and Wildlife Acoustics Echo Meter Touch 2 all have real-time sonogram display (Pettersson M500/M500-384/U256/U384 & Wildlife Acoustics Echo Meter Touch 2 when connected to suitable device) and the Anabat Scout, Peersonic RPA3, Elekon Batlogger M and Pettersson D240X & D1000X do not.
The Echo Meter Touch 2 connects to compatible Apple or Android devices.
If the real-time sonogram display is important to you, I recommend either the Anabat Walkabout or the Wildlife Acoustics Echo Meter Touch 2 PRO. If you don't want the display it would be the Elekon Batlogger M (which can be used passively as well) or the Anabat Scout.
Choose whichever one has the features that suit you best and if you need help choosing, give me a call on 0333 9000 927 (+44 333 9000 927 from outside the UK) or email me.
You'll get a free bat calls book worth £30: either British Bat Calls by Jon Russ, Social Calls of the Bats of Britain and Ireland by Neil Middleton et al or Bats of Britain & Europe by Christian Dietz & Andreas Kiefer; with the Anabat Walkabout, Elekon Batlogger M and Pettersson D240X & D1000X.