Comes down to a few things. What devices do you use? You don't want get a soundbar with only 1 input and then find out your can only listen to the sound when it's on TV but your chromecast or roku or whatever only works through the TV speakers still.
What TV model do you have exactly and what devices do you use. These two things really need to be considered when buying a soundbar and most people don't then are disapointed when they can't use half their devices with it.
Of these only the Samsung seems like a decent product according to it's spec sheet at least. The vizio has really small speakers and only goes down to 60hz so it cuts off a little high for my liking, the Insignia is a little underpowered and doesn't even give you speaker sizes or frequency response figures on their website. The samsung seemingly has decent specs though, but I really wouldn't recommend a sound bar if you care about your audio quality unless you have a serious need to not have speakers for some reason. At least it has a sub which means the low frequencies are less likely to muddy the sound of the main speakers.
My tv is 55 inch insignia, I'm not an audiophile by any means, all I need is a sound bar than will let me hear dialogue , with my current tv is impossible to hear dialogue when something else is happening like an action scene, we have to be constantly highering and lowering the volume of the tv. Also someone told.me 3.0 channel is a lot better than 2.1, how true is that , I have a separate subwoofer I can plug into the vizio one as it has an input for that.
If it's three channel (center, left, right) then why does it only have 2 inputs, either stereo through a 3.5mm (headphone jack) or the dual RCA? Unless you are hooking it up via the optical and it actually does pick up the center channel that way.
Every sound bar I've heard except for really premium products has had pretty disappointing sound. With a sub it might not be so bad but I can't see any way to adjust the crossover frequency to stop your low sounds from being sent to the sound bar speakers which is usually the cause of distortion (which is probably what is happening on your TV).
I haven't actually heard the Samsung one, but I'm pretty sure the setup would be tuned to to have the crossover set at a proper point for their own speaker/sub combo.
Since you are concerned with clarity the 3 channel Vizio will at least have a separate dialogue speaker. If you connect it via optical and can set your TV for surround output (rather than stereo) it will be clearer. Check the TV owners manual to make sure.
Since you have a sub why pay for another one that may not be as good.
None of them seem to have a woofer and tweeter which would enhance the clarity of dialogue. Your price range limits you. You should find them to be better than the TV speakers but maybe not enough better to solve the problem. They all will play louder than your TV but that isn't your complaint.
Specs on soundbars are not regulated or standardized so you can't assume they are accurate and can be used for comparison.