My favourite mod routing is to (and this is for the punchy ones) set
Attack 0
Decay 18-ish (you'll tweak this later)
Sustain 80-100
Sustain Slope to its max negative value
Release 0 - experiment
Now, set up the modulation:
Source: Amplifier envelope
Destination: Amplifier decay
Amount: -3 - -10 area
Next, fiddle with the decay knob. I found that doing this you can have your patch sound almost as if you're triggering a sample. It will always stop abruptly after whatever value you set decay to.
On many occasions it also works great to lock the osc trig phase at 32. However, if you get that (which I call it anyway) "cheap softsynth-sound" on the attack, then turn it off unless you're after that. I do this on patches that I want to have stabby and punchy.. When I was new to the virus I always set A0 D0 S127 R0, wanting LOUD! STABBY! patches. It is much for effectful to do more of a A0-5 D18-30 S80-100 R0-10 thing. And then give the decay a touch of modulation by the amp env itself, and you give it more character. You probably need to compensate by either increasing the patch volume, or lowering the other elements.. Having this envelope setup will also sound better when compressed a bit, as it has that small decay to work on.. imho
All the parameters needs tweaking against each other, of course, but I think this should serve as a starting point.