Which monitor model do you have at the moment?
Do you have a size in mind?
I would go with 144Hz tops, since most of us cannot tell the difference above that.
How about this units
ASUS VG248QE - 144Hz 24" 1ms
BenQ ZOWIE XL2536 - 144Hz 24" 1ms
Alienware AW2518Hf - 240Hz 25" 1ms