I had Pod Farm 2, Gearbox before that, and now I have Amplitube 3 with the Orange, Fender and Ampeg SVX, and Soldano add ons. I just can't get into liking them. Believe it or not, using low res on Amplitube helps. To be fair, the bass amp sims do sound pretty good. I just don't get the hype about them though. To me, there is just too much harmonic response or saturation or whatever. Maybe if they did impulse cabs as opposed to whatever they do now?

All of the Amplitube amps you mention sound excellent to me. I believe the guitar contributes to the quality. Maybe you have some settings that could be adjusted?

Example of Orange sounding awesome:
http://www.youtube.com/watch?v=bg6SaKk0mms

How close are your studio monitors to actual guitar amp cabs? That makes a huge difference. I have a set of JBL studio monitors (4312's) that have 10 in speakers with 10 1/2 lb magnets behind them. When I run the Marshall amp from S-Gear through it, it sounds stunningly authentic and this is running alongside actual tube amps -blackface Princeton, Hot Rod Deluxe, etc.

Huh, I've sometimes wondered how a good amp sim would react outputted to a speaker located in a typical guitar amp position instead of where monitors typically sit...
 

I thought the whole point of an amp sim was using regular monitors as opposed to an amp cab? I can usually get the clean stuff to sound decent but distorted is out of the question.

I do notice that Pod Farm 2 sound better than Amplitube though. Pod Farm only has one input whereas A3 has two. I had it set so both inputs were used. I then set the second input to an unused input and it sounded better. I haven't tried setting the pan to either left or right but I don't see why that should matter but I'll try it anyway now that I just thought of it.
 
I don't have proper monitors though. I have an old set of Linear Dynamic consumer speakers. I know I should get proper monitors but this is the best I can do for now. Maybe I should do what I do for mixing. Check against audio either CD or online radio.

Yeah. I could have expressed my thought much more clearly. I was referring to monitors having approximately the same weight and power necessary to drive them as guitar cabs not that they should sound colored like guitar cabs. Another way of saying it is - I would not expect smaller speakers would be able to create the sense of realism of beefier monitors.

Amplitube is good stuff. It should hold its own when compared to Pod Farm 2. Maybe try tweaking the gain going into Amplitube?

It is possible you just have amazing sensitivity to guitar sounds and sims can't meet it, but more likely there's something about your setup that's an issue. I find Amplitube 3 to be extremely good. So some possibilities:
 
1) Speakers. As noted, they need to be competent to reproduce the range of tones you want. If you have itty bitty desktop speakers that are competing with a huge guitar amp, well then they aren't going to sound near as good. So the question is, do your speakers sound good for guitar that's been recorded from an amp or not? If they sound good there, but not on the sim, then they probably aren't the problem. However if you mic and record an amp and the playback on your speakers is dissatisfying, well then that's likely the culprit.
 
2) For live guitar recording, the input matters. Do you have a proper input that is working well, and is setup for a guitar? This means capturing without digital distortion, or crackling, or skips or whatever. Make sure you check the dry track and that it sounds clean. If not, then you need to fix that. Also, a mic or line input isn't suitable for a guitar. Mic inputs are generally 600 ohms, line inputs in the 10k ohms range. Guitar inputs need to be like 400k ohms minimum and usually more around 1M ohm. If you don't have one of those really high impedance inputs it snarfs up the highs and sustain and makes your sound very dead. So you either need a card that has an input that can be switched to a high impedance mode for guitars, or you need a DI box to give the guitar a high impedance input and convert it to low impedance for your soundcard.
 
3) For sampled guitar, the quality of samples matters a lot. The Strawberry Electric Guitar is the one I've tried that makes me the happiest. Direct Guitar 3 is also decent, but noticeably inferior. So if you are using a sampled guitar and it isn't EEG Strawberry, maybe look at getting that. I particular if you are using samples they MUST be dry, feeding already amped signals in to an amp sim never gives good results in my experience.
 
4) Gain staging can matter with an amp sim. While with many FX gain doesn't matter much in the digital domain since floating point math allows for tons of headroom, that's not the case with amp sims. You need to make sure the signal level going in is appropriate, not too loud not too soft. Mess around with that some, see if it helps. I find a good sample like Strawberry is already at a good level, but others might not be.
 
5) If there's too much high harmonics for your taste, try what Craig Anderton suggested: Toss a steep EQ on the signal BEFORE it goes in to the amp sim. Put like a 48dB/oct lowpass filter at 4-5k using Pro Channel or another EQ before it goes in to the amp sim.
 
When given a good signal, I'm amazed at how good Amplitube sounds personally.

Don't know about Amplitude but Line 6 Pod Farm is very sensitive to input gain. What looks like a good track level is  2 hot for it. I had stopped using their DI because I thought the output level (clean track) was too low but recording a hotter track made the plug-in sound bad - off color & kind of lifeless. 

I have a long love/hate story with them. I own tons of them. Sometimes they work surprisingly well, others nothing I try will work.
 
I've learned not to draw any formal conclusion because I've heard people getting amazing results with each of them. 
 
IMHO, impulses often sound smoother but tend to be static - something you can compensate for by using multiple impulses, in part. By comparison, Amplitube's cab modelling is incredibly dynamic - but I'm not always so sure about the sound itself.
 
Though there are models I truly like - their Hiwatt, for example.
 
The problem is that, if you're not entirely satisfied with a sound, even if it's just that elusive little something that is missing, you'll start to analyze and soon enough, you're sucked into it and all you hear is those pesky details - which, often, aren't half as bad as we believe when we're over-analyzing it.
 
But it's hard not to fall in that trap.
 
Overall, I've had more consistent results w/ hardware, even though I'm rarely entirely happy w/ it.
 
 

Rain, real amps have the same drawbacks. Especially, TUBES! Sometimes you turn them on and the angels sing and you turn 'em on the next day and they sound like crap. I have wrestled with getting good guitar sounds recorded my whole life. In the process I acquired dozens of amps, guitars, stomp boxes, guitar synths, etc.. Not to mention a collection of mics.
I go on record here, as I have said in the past: Nothing will ever beat a good tube amp with a high quality mic on the cab.
I learned from Tom Dowd and Les Paul the art of mic placement and that kind of thinking carries over to my use of amp sims. When I use amp sims I try to think along the lines of having the hardware sitting in front of me.
Amp sims are making pretty good leaps as far as getting more realistic.
Like you, I have quite a collection of amp sims and PODs and GTs. I am happiest right now with the full version of TH2. No, you don't have the capabilities of a Kemper or BIAS. But for what it is it fills the bill very well for me. Notice I say the full version. Everyone that knows my posts probably thinks I am a salesman for Overloud. I just know that my work became faster and I am happier with the results since using TH2. The Brunetti amps are worth the price!
I still pull out an amp and a mic from time to time when a client just has to have the REAL deal. Most times, I use TH2 and no one ever knows the difference. As a matter of fact, if I used Amplitube or GR or my PODs they wouldn't know the difference either.