In LCD, Samsung is the leader right now for sure. But there are solid sets made by Sony, Panasonic, and Sharp (the Aquos line) as well. Also, Toshiba and LG make good models from time to time. Their overall lines are not as strong, but they have some models that perform extremely well. And opposite to that some Samsung models aren't really that great at all (like the series 3 TVs). So in the end you need to do a model by model comparison to be sure.
Of the models you listed the first and 3rd ones are the good ones. For a 46" LCD you want/need the 120Hz technology. It doesn't bring it to Plasma quality, but it helps a lot. While Plasma is overall better than LCD, I wouldn't necessarily go Samsung Plasma. That's not what they are known for. I'd look at a Panasonic Viera, maybe TH-PX80 or PZ80 at 42" would suite your needs.
As for overall, Plasma vs LCD...
LCD - is the everyman HDTV. It is cost effective, hence its popularity. It is also physically lighter than Plasma. It tends to draw less power than Plasmas as well (though good Plasmas are now beating LCDs). It has a matte finish so is useful for rooms that have too much ambient light which can not be controlled. LCD whites are a bit brighter than Plasma whites (but how often do you crank your brightness to 100%). LCDs are considered better for gaming (but I don't think you'd be disappointed with gaming on a modern Plasma). LCDs are sharper in SD (think evening news instead of film); this isn't a good vs bad, its just a personal preference thing.
It has problems with fast motion though. That is why you see ones advertised with 120Hz refresh rates. This does not come close to Plasma though. So they aren't as good for fast motion (sports and movies). The new 240Hz ones with LED backlighting are making good strides, but right now you're paying a HUGE premium for those features.
Plasma - they have better blacks, contrast, and motion blur. They are better TVs, but you often do have to pay a bit of premium for them. Images look smoother. They have greater ranges in blacks/whites so you get greys instead of clumps of black and white. The colors in Plasmas tend to have more "pop" to them; this isn't a good vs bad thing, its just personal preference. Plasmas are great for fast motion (sports and action movies).
Plasma's are glass though so are glossy. They can have reflection issues if you are in a room with lots of light that you can't control (you can't turn off the lights and you don't own any blinds). Also for SD viewing they are a bit "softer" (think more like film less like the evening news). This isn't a good vs bad thing, its personal preference. Most plasma owners get used to it and don't mind it.
They do have to be conditioned. The gasses of new Plasmas need to be conditioned. All you have to do is keep the brightness/contrast cranked way down for the first 100-200 hours, then optimize, and you'll have an amazing TV experience.
Plasma myth (1) - They experience burn-in. This is BS, those days are gone. Just condition the gasses and then use it as normal and you're fine. Also, the better sets have built-in features to prevent this (on top of the technology just generally being better now than say 5 years ago).
Plasma myth (2) - They have short life spans. This is more BS. You can leave your Plasma on 24/7 for 34 years before killing it. So do you think you'll still want/own the same TV in 15 years, let alone 30?
Plasma myth (3) - They won't work in high altitude because of problems for the gasses. This is again no longer an issue. Current Plasmas can be purchased and used in mile high Denver, and above, so you'll be fine where ever you are (unless you're living in the Himalayas).
Plasma vs LCD - One important note though is TV size. In 42" and above you see and get the benefit of the Plasma advantages. But 40" and smaller and the benefits are diminishing. So if you're going way smaller than LCD is likely the better option.
Plasma brands - Pioneer Kuro Elite is the best, followed by Pioneer Kuro. But these can cost as much as a small car. Panasonic Viera is the next best and is much more cost effective. Then I would go with Samsung. The Panasonic TH-50PZ800 or Samsung PN50A650 would both be top notch choices.
LCD brands - I would stick with Samsung, Sharp Aquos, and Sony (but only Sony if its on sale, otherwise it tends to be overpriced). Sony stopped manufacturing LCD panels, they now buy/use the same ones used in the Sharp Aquos sets. Samsung is a step above the rest if you go with the 5, 6, 7, or 9 series models.