As I said in the OP, it seems to just be me.
Thought I'd let you guys get some giggles about the ridiculous levels he reaches on some of these barbs.
While discussing a plant that I've kept alive for ten years (which I thought was pretty impressive) "Oh Lisa can grow anything. She has houseplants that are as old as she is and they just thrive!"
While discussing books "Oh Lisa reads much better authors. She has such good taste in literature."
While discussing an outfit someone else complimented me on, "I'd never choose something like that. It's not flattering on you at all. Lisa's sense of style is so much nicer."
While discussing an online game that everyone got hooked on for a while (I had gleefully told my score to someone) "Is that all you've gotten? Lisa made 54, 4478 points in just two hours yesterday. I guess not everyone can be good at that sort of hand/eye coordination stuff."
While discussing a stupid trip to the grocery store! "Lisa is a much better bargain shopper than that! She always saves us at least 50 dollars at the store and we eat like kings!"
And here's the real kicker- I was talking to a friend who asked me about my crocs, which are tan he said "Lisa doesn't wear those ugly things. And if she did, I'm sure she'd pick a more lively color. Tan is really unoriginal."
The croc thing really got me. I was like "Dude, they're plastic shoes! Who cares?" to which he said, "Well, women should always be conscious of looking cheap." I thought, whoa, did he just call me cheap? Then my friend asked him that exact thing at the same time Dh walked up and asked what we were talking about. Dh, who also had on a pair of tan crocs! John changed the subject.
I'd love nothing more than to advise you to laugh at him (I did that once to someone who was being beyond dismissive/pushy with me and it worked!), but unfortunately I think this really is an insecurity issue so that would just make it worse.
First of all I'd stop being around the jerks. I'd flat out refuse to be in the same room with them, ever. If that's not an option then it's time to say something.
John: Blah, blah you suck and my wife rocks.
You: *calm tone, head tilted, quizzical expression* Why do you do that?
John: Do what? Why are you so sensitive?
You: I'm not oversensitive. You insult me every chance you get. It used to really bother me and I spent quite a bit of time trying to figure out what I'd done to offend you. But then I realized I've never done anything, so you must just enjoy it. So again I have to ask - why is that?
John: No I don't. It's not my fault if you can't handle me complimenting my wife.
You: Of course I can, your wife is lovely. But you always, without fail, make a comment about something I'm saying/doing/wearing/reading/etc. and insult me and tell me how Lisa would do it so much better. Why do you do that?
The key is to be consistent - every single time he does this to you remain calm and ask him in all seriousness "Why do you do that?". This guy KNOWS he's doing something wrong, that's why he keeps his mouth shut when your Dh is around. Call him out! It might take a time or two but I bet you he'll quit. In fact, best case scenario he avoids you all together - it's a win/win!