I use Reaper. It is fast and clean and no bullshit.
While the session view in ableton is good it is still little bit overrated since
You can do the same thing from midi and trigger samples that way.
One thing about making ambient with a DAW is that the actual DAW is off less importance since
this music does and should not rely so much on offline editing (besides this glitchy crap ambient)
Making ambient with your daw atleast for me
is more about setting up enough parameters with your midi devices to control your synths and plugins/daw in real time.
With your midi you can also control your daw. Once you know how your parameters react you can almost shut down your monitor
in ideal conditions. It is not easy to recrod and perform ambient live, but you need to realize that looping is probably the best way to do this, Robert Rich is a good example. only with 4 track looper you can do very interesting stuff and and because the loops does never meet each other in the same time the variation will be endless..especially if subtle changes are made.. biggest misstake when creating ambient is probably of doing to drastic and big changes.. when you put your headphones on laying in bed listening you realize it is all about the small changes in the soundscapes if you really sink in deep enough into the sound world.
The DAW can be a major distraction when creating trance inducing music, you want to be as far away from the "intellectual" state of mind as possible when you are floating with your soundscapes, being as far a way from your intellectual self will make you create deeper trance inducing ambient and less superficial.
Anyway if you are trying to get away from getting stuck in your daw and want to do real time improvisation
I have not tried it myself but there is a program called VIP it is currently released on akai advance and Alesis VX series
This software is a fresh wind in the context of midi control.
If you think the Alesis synth look very similiar to M audio Code it is because it is because the same company own akai, m audio and alesis, that is why all 3 companies will use VIP software in future.
Using VIP you can record music with all your soft synths and midi keyboards and surfaces without any daw at all.
in fact.. you can split up your keyboard so certain zones play lets say the plugin omnisphere zone 2 will play Native instruments Monark.
You can use mutple plugins for the same zone/keys too. Only your cpu sets the limit..(Broadwell-E with 10 cores is released 2016 Q2)
Of course all this can be done in DAW already but look on you tube the whole work flow is very simplified.
You can control the plugins completely from your midi synth display which is kind of slow (unsure if it is possible to connect your ipad or such to get bigger touch surface for the display it would be the ideal)
The Alesis VX49 is pretty much a m-audio code but with Alesis logo plus VIP software.
I am not saying that VIP is the prefect thing but it is certainly a fresh wind into the midi market and considering most people use software these days this is really important. If you want to see how it works just use youtube.
I would most likely buy the ALesis synth if it wasn't for the fact that M-audio have promised a more high end series which will also include VIP software in about 2 months, considering how good the M audio Code is it is simply worth waiting for, hopfully they will not make me wait 2 years like behringer did with their "motör" with its motorized faders which never seem see the light of day...