You need no other synthesizers. Nearly all of those that you listed can do new-age pads with ease. Zebra for example. You've invested at least $1000 in soft synths:

Sylenth: $240
Zebra: $199
Synplant: $99
Omnisphere: $499

There are tons of great pads available in those synths.

What specifically can't you do - can you point to a specific sound in a particular song, because I've just randomly picked a Karunesh song and a Mike Rowland tune, and I hear nothing that I can't actually output from my kids Casio WK200.

Here's something to keep in mind - nearly every modern music production that uses synthesizers heavily is using automation to change some parameters. For example the Mike Rowland tune (Listen to Your Heart) that I'm listening to right now has a very simple warm pad, but it does sound like the filter cutoff is being very slowly modified. Very easy. You can do this with many freeware soft synths as well.

Here's what I suggest you do:
1. Don't buy anything else - you have all the tools you need
2. Pick ONE song, with one target sound and critically listen to it. Do you hear it move from a timbre standpoint throughout the song? write out notes on the sound's characteristic
3. Pick one basic pad from one of the least complicated synths you have purchased. I suggest Sylenth, as it has the most 'conventional' controls from a subtractive synthesis engine of those that you have mentioned. Look at how the pad is constructed in Sylenth, and extremely change one parameter at a time. Make notes on how this sounds. Pads nearly always have a slow attack for the volume envelope, you can tweak non-pad sounds to have a slow attack delay and release to go with. Also, add reverb - almost as a rule.

4. Here's some free presets for synlenth, some of which are pads.
http://www.kvraudio.com/banks.php?s=list&product=2500&order=date

5. Don't spend anything. If you are still stuck, at least send me info on #2 step above, and I'll redo it on some freeware synths.

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