I'm not too familiar with Lexicon or Aragon, but I am with Sunfire and Krell. I owned a Sunfire TGIII and I absolutely loved the sound, but after having a few operational hickups with the TGIII I thought I should try something different. Well I then purchased an Integra Research RDC-7, it's a fabulous unit that had everything I was looking for and then some. The only thing was that after using the RDC-7 for a month I realized that it wasn't the best match for my Martin Logan speakers.
The Sunfire really made my Logans come alive, with a sound that was warm yet detailed and dynamic. Well, I missed the TGIII so much that I just recently returned the RDC-7 and ordered me another TGIII(this time it's staying). So needless to say I am very fond of the Sunfire TGIII,and I highly recommend it.
Krell is another very fine performer, and another that I highly recommend. I haven't owned a Krell Showcase but I have done some very serious auditioning. Like the RDC-7 the Krell isn't the best match for electrostatic speakers, but for speakers like yours it should work really well. I feel that both the Sunfire and the Krell do a wonderful job with both music and movies. I don't think you will be dissaponted with either.
The best thing to do though is to carefully audition the pre-pros that you're considering, that will be the best way to know for sure if you like their sound. And if you can do a home audition that's even better(what better than to try them with your own speakers). I don't recommend buying something sight unseen, as it might look good and seems to be what you want, but you won't know what it's going to sound like until you have it in your setup(which may not be a good thing). I'm sure you'll make the right choice.
I wish you all the best on your search.