The Samsung and Plextor you have listed are premium drives with premium performance, hence the extra few dollars. All 3 are proven performers and if you aren't looking for the top of the heap in terms of performance, save a few dollars and get the Crucial M4. Several forum members have one and they perform very well and are reliable. If I had to buy one today for a rig I use everyday, I would get the Samsung because it is, as of right now, the fastest MLC SSD on the market, and will likely be as reliable as last generations 830.
If you can afford the extra 30 bucks, get the Samsung 840 Pro. If you don't need the absolute fastest SSD out there, get the Crucial M4 and save the money. Any of those drives would be good though.