If this is for gaming, then having dual monitors is not really recommended if you are playing a 1st person shooter since the target rectal will be directly in the middle separated by the bezel of both monitors.
I have a dual monitor setup, but I only use the 2nd monitor to watch videos while doing things on the 1st monitor, or when I am doing some heavy multitasking when a large desktop area is very important.
If you are happy with the Samsung, then just buy it again so that you have matching monitors. Buying a different monitor could mean that the screen itself might be a little higher or lower than your Samsung. Not a big deal if the new monitor has height adjustment, but most inexpensive monitors do not have that feature so you may need to use something like books to level both monitors to the same height.