Your Amiga won't mind or even know that you're using the A520 and/or the A2320 output or even the mono composite output.
As Mike said earlier, if you'd like the best picture on a VGA monitor you'd be best to purchase an IndivisionECS.
http://amigakit.leamancomputing.com/catalog/product_info.php?products_id=918If you want a new monitor, then you might want to read this thread from start to end:
http://www.amibay.com/showthread.php?72457-BenQ-BL702A-perfect-monitor-for-amigasBenQ BL702A does work with the Amiga series without anything extra, but you will need a buffered VGA converter adapter for your Amiga video output port on 'big box' Amiga's, as yours is an A2000. Read the last page regarding the Dell monitor... it gives the best picture by far but it doesn't remember screen position!
I'd sway towards an Indivision. But, how about getting a 1084S or something for the authentic experience?