my advice is, always get the biggest lcd u can afford. if 2,500 ra difference, hunati saln for a few more weeks or months na tigum. magmahay rka if makapalit naka den u realize na gamay ra diay. ang imu monitor is not one of the components u upgrade regularly like the gpu or cpu. its relatively more long term. i got a 24 inch asus and now i regret not getting a 26 or 28. same thing happened when i got a 19 samsung and i regretted not getting a 22...
also as to brand, just make sure whatever brand you get has a good, tried and tested warranty service.