Well I had no chance to get my hands on an Ableton Push yet, but it looks awesome.
Besides that the Launchpad of course is nicely made to ableton and the out of the box mappings work great.
The Midi Fighter (there are many types) some of them have Ableton mappings out of the box, but of course any MIDI controller can be mapped to work with Ableton. So a lot of it is personal choice. The Midi Fighters really take abuse, so if you are a hard button pusher, those arcade buttons work great and config software is really good.
I have no experience with the NanoPad, but I have a Vestax Pad that is reasonably cheap and works great for smaller things. I had to map it myself however…
Ableton 9 has a lot to offer customisation wise for mapping controls, so there is a learning curve, but also good tutorial videos…
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