Hey, I take offense to the geek-comment.
I'm a member at AVS, (and HTL, HTF the old HTT, etc.) Beer brewing became my second hobby after home theater got too expensive.
The answer really depends on a few factors:
I'm going to assume you really want to know between Plasma and LCD for any number of reasons, and I don't know that much about DLP so I won't comment on it.
Plasma
Pros: Better (IMO) picture quality, black levels are deeper, colors are better. Lots more choices that are half-way decent in quality and the price, especially at the larger sizes. At 42, you're right on the cusp of either one price wise, though.
Cons: If you have a well-lit room, with lots of windows, you'll get a glare off the reflective coating on a plasma screen. I live in a cave, by my own choice, so this doesn't bother me.
Potential burn-in problem but this has been so overblown that it isn't even funny. Any new plasma is essentially burn-in worry free, assuming you're not watching a static image for days and days at a time. Assuming you watch TV like a normal person, and change the channel once in a while you're fine. I game on my 4 year old plasma and have no problems, and have been gaming on it since I got it. If you're interested in 1080p (1920x1080 resolution) it's a little more expensive in plasmas. Only the best of the sets have decent scalers. If you're interested in a plasma, depending on budget, I highly recommend anything by Pioneer or Panasonic. If cost really isn't a factor, you CAN'T go wrong with the new Kuro Plasmas by Pioneer. They're really outstanding.
LCD
Pros - Can be seen in a well-lit room a lot more easily (also why they looks so good in the Big Box stores with all the ambient light.) No burn in to worry about. 1080p is almost a given, which is nice
Cons - (and this is a personal preference) colors suck on all but the best sets. They appear, to me, to be washed out and blacks appear to be grey. I find that LCDs have a motion blur on fast moving scenes. For example, I haven't seen many LCDs that I would be able to watch a hockey game on (or even football, though that doesn't move quite as fast.)
If you're considering an LCD, I like the Sharp Aquos, and Sony Bravia sets. I've also heard great things on the new Samsung sets but have never seen them in person so I can't comment on them.
As for the half-life of plasmas, that's another mis-information propegated by the Pro LCD folks. The 20,000 hour half-life was true 8 years ago. Now they all claim at least 60,000 hours and, like I said, mine is almost 4 years old and is still running strong. I'm only thinking of getting a new one because I want a bigger TV.