Enhancing Guitar Punch & Dynamics - What Method/Plug Do You Prefer?

I need something that will latch onto the attack transients so I can accentuate them.  I set my gain amp profiles in a way that still allows for some dynamics to sneak through - a balance between having just enough gain to remain playable while recording.  So I usually have a bit of dynamics, just enough that I was hoping some plug might be able latch onto the attack transients so I could accentuate them (overly so if necessary and then re-combine in parallel processing fashion).
 
Already tried a few compressors without much luck....
 
Sonic
 
 

give sknote grasso a look

I'm using a Kemper at the moment. It has great speaker/IR emulation, however I find the amp emulation is a bit compressed compared to a real amp, so the end result sort of cancels each other out. 

As mentioned above is hard to get the attack back, and without hearing the material I am not sure how effective this would be. MPhatik is more designed for drums, but I just tried it on some guitars. The preset "Warm Up with Attack" did have decent results on the track I was playing with to check this. You can check out the trial and see if that does anything for you.

When trying to get a killer guitar tone, you've got to think like a baker :). You'd be surprised, that if you know what you're doing and understand how the rock-avant-gardes got their tones - then you can get great tones using guitar sims...well at least with Guitar Rig.

First to get the killer tone, I would either use a tube preamp or use the Prochannel tube sim. I actually use the latter but in the past I've used a 'real' one. I actually prefer the tube sim these days. What the sim does is level the signal and add some 2nd level harmonic distortion. Just use your ears with distortion. The signal gets a bit of sparkle is what you're listening for. -6db output and +3db imput are good starting points for the leveling.

Now one of the most important things I learnt early on is how David Gilmour gets his tone. His tone requires a foot pedal compressor somewhere in the signal chain. So for me, to get those long sustained notes, I would use a compressor before the amp sim. I tend to use Wave's plugs for this job...mainly because you can then emulate the signal chain of classic recordings. If you were after more punch and a more metallic guitar sound then I'd put the compressor after the guitar sim.

Another important idea is to understand amp types in the Sims, and this is where knowing some history is good. Hiwatt amps were favoured by Pink Floyd and The Who, Vox by The Beatles and Queen etc. Also try opening up the sound by using the air and microphone controls on the amp sim. And finally EQ and again try finding a tasty one like Kramer's Helios EQ. Oh and console emulation.

If you follow these steps you will get that killer guitar tone using amp sims. You can find examples of my guitar tones in my signature link.

Hope that helps.