Roland Alpha Juno 1
This keyboard is the first "studio" keyboard I bought (no internal speakers). I use it on almost every single song. The older Roland Juno synths are very famous for their unique analog sound. The Alpha series were the last of the true analog Roland Junos. I think they have a sharper edge, but are not quite as "fat" as their father and grandfather, the Juno 106 and Juno 60, respectively. I use this synth mainly for leads and basses, but occassionally it has just the right sound to flesh out a pad or provide other sorts of supportive work.
Roland Alpha Juno 2
I bought this synth because it had a great "buy-it-now" price on Ebay and I wanted another Alpha Juno since I was having to constantly sample my Juno 1 to free it up for another part in a song. The difference between the Juno 1 and Juno 2 is that the Juno 2 is velocity sensitive, has one more octave available on the keyboard, and has a memory card option for storing patches.
The CS2X is a great all-around wavetable synth. It has good selection of sounds for uses in all different situations. I use it mainly for its selection of pads (which sound excellent), but you will find bits and pieces of its sounds throughout my songs. I think it has the most analog sounding digital filters I have ever heard -- even to this day. The LPF sounds so rich and can create a huge amount of resonance.