The two plugins I'd love to replace are the Waves S1-Shuffler and the Doubler-2 plugins. The Shuffler is great for correcting or enhancing the stereo image, and the Doubler is fantastic for spreading things over the stereo image and doing chorusing/thickening. I *can* recreate that one with plugins and make an effects chain with just Sonitus plugins, mind you, but the Doubler is super elegant and just works.
 
Aside from that, I agree with what others have said - a great frequency / phase meter plugin with a snapshot memory like the Waves PAZ series would be brilliant.
 
The CA-2A, LP multiband and EQ, and the Adaptive Limiter are my go-to effects these days, which I'm absolutely loving!

I would vote for meters.

I would love to see a remake of the  Channel Tools plugin. I find the stereo width portion of that plug really wonky to use. It would be great if it was a prochannel module because you could display multiple instances more easily.

A refresh on the quad-curve EQ would be nice too. I'd like to see a makeup gain adjustment added and perhaps presets.

It would be pretty cool if cakewalk and Overloud worked out an update for the console emulator as well.

RSMCGUITAR
I would love to see a remake of the  Channel Tools plugin. I find the stereo width portion of that plug really wonky to use. It would be great if it was a prochannel module because you could display multiple instances more easily.

A refresh on the quad-curve EQ would be nice too. I'd like to see a makeup gain adjustment added and perhaps presets.

It would be pretty cool if cakewalk and Overloud worked out an update for the console emulator as well.

I wish they would release the Boz and Joey Sturgis Tones "Sidewidener" plugin as a pro-channel.  Easy enough to have all the functions in that space.  And Boz is already known to work within the format.  And the plugin is already great.
 
As for everyone that wants better metering.  Things like this look good and are free and well regarded in general (though it would be nice to have something similar as a PC plug).  Though depending on where you put the PC in the effect chain, it could be limiting.
 
http://www.tb-software.com/TBProAudio/mvmeter.html
 
 

I think cake should show some love to the Sonitus plugins, these plugins have been flying under the radar for years, if you haven't tried them, you're missin out...

Primetime
I think cake should show some love to the Sonitus plugins, these plugins have been flying under the radar for years, if you haven't tried them, you're missin out...

I agree whole heartedly....

Primetime
I think cake should show some love to the Sonitus plugins, these plugins have been flying under the radar for years, if you haven't tried them, you're missin out...

I'm pretty sure this would have to come from Ultrafunk: http://www.ultrafunk.com/
 
Rocky

The Sonitus plugins are fantastic. It's a shame people write them off for being "old looking" because they're pure work-horses that just get the job done with no fuss.

bluzdog

Primetime
I think cake should show some love to the Sonitus plugins, these plugins have been flying under the radar for years, if you haven't tried them, you're missin out...

I'm pretty sure this would have to come from Ultrafunk: http://www.ultrafunk.com/
 
Rocky

Sonitus: 1998 - 2003. . Wow.
These plug ins were top dogs in their day and are a bit dated now, however those plug ins still have major flexibility.
For example, the Sonitus Delay I still use on almost every project as it has independent side to side time sliders and while its mostly transparent, it has a nice coloration . The thing I love about it most is it reminds me of one of my hardware units: The Digitech RDS 1900.
 
The RDS 1900 is not greatest hardware delay in the world but back in the day, I was able to squeeze every once out of that delay. I'm able to do similar things with the Sonitus Delay as well.

As a rank amateur, I feel I've got mastering tools that are well beyond my talents and needs coming out of my ears. (I'm almost embarrassed that I own the full-blown Platinum version, it's well beyond my simple needs, but a metaphorical alignment of the planets allowed me to grab the lifetime updates deal at the 11th hour).
 
Some form of more creative VST would please me. Due to my current impecunious circumstances, I rely on what comes with Sonar and some of the freebies out there. Other than getting Waves IM Pusher for £17 (I had a $30 off coupon) in December, my last VST purchase was in 2009!
 
But if the Bakers were to ask me what I'd really like, I'd say: take the best bits from Beatscape, DropZone, RXP and Cyclone, and make the instrument you should have made in the first place.