Jeppessen Flite Pro and the Elite products are first rate for what they are indended to do. My ASA experience was not as good, perhaps because they buy the product from a manufacturer that never hears directly from the end users. If you buy the Jepp or Elite systems, you will pay top dollar. The radio stack module on the Elite system is especially nice, since it works just like the one in the plane. The Jepp is a little more "unique", but works well.
I use FS 2000 at home to keep my scan up. I have an old serial CH Virtual Pilot Pro yoke, and I can fly holds and approaches with almost the same realism as the high priced spread. One major difference is log-ability. The FAA has an advirsory circular that details the requirements for a PCATD (which is what they call what we are discussing) that is to be used for loggable instrument training. FS 2000 isn't loggable, but will help you build proficiency. Most of the time, it's all you really need.
Yeah, they are all good, but why not get a program you can learn with and have a little fun on the side? Flight sim 2002 allows you to practice the same things as those you mentioned plus it allows you to play with the heavy iron. You can practice holds, fly ifr (and talk to atc), approaches, partial panel. You can add wind, and reference map view for your progress. Also, flying the heavy iron will get you introduced to fms, autopilots, and flying fast, stablized approaches. It is more expensive though. I guess it's all up to you. If you pick from the ones you listed, I'd go with Jep.
I agree with flyboy - if you're just looking for a sim to keep yourself sharp and don't intend to go all out with the gadgets to make the time loggable - I'd suggest looking at some of the consumer sims. I personally use X-Plane (www.x-plane.com) for all my PC flying needs. It hasn't let me down yet for practicing all my favorite approaches and procedures, and it's nice to fly a new route or approach a couple of times in the sim to get familiar with it before launching into IMC in the real thing.
The only thing lacking is a good ATC communication system. Both FS2002 and X-Plane have the basics, but there's really not enough there to do an actual pilot any good from a proficiency standpoint. Dunno how well the more expensive sims do with this...