While it is not strictly speaking a scaler, in the sense that it cannot scale input to a specific target output resolution, an OSSC is probably one of the better options.
The OSSC can digitize, optionally line multiply ("scale" by an integer value, within its frequency limits) and output through DVI ( most if not all monitors support DVI signaling through an HDMI input with a passive adapter or DVI to HDMI cable). It does require a monitor capable of setting a true force 4:3 mode (for proper display of non square pixel modes, like VGA 320x200/640x400 ) and able to sync to some non standard modes (note usually an issue on most monitors I have tried, especially among monitor capable of accepting and displaying more than 60Hz). VGA modes that are 70.08Hz will stay at the refresh frequency.
More flexible and expensive option, like OSSC Pro and RetroTINK variants also exist. The CRT Terminator is also a potential option.
On the flip side, if you do not mind a scaler/digitizer that converts everything to 60Hz abd to standard resolutions/timings all monitors support, does not require a monitor with a forced 4:3 mode and is likely much less expensive than most other options (only on the second hand market ), an Extron RGB-HDMI 300 or Extron RGB-DVI 300 variant is likely still the best option.
All these and other options are discussed in this huge thread What are the best Vga to hdmi scalers or peripherals for MS-DOS games ?
P.S. Using an LED/LCD monitor's VGA input, regardless of it being old or new, will cause some visible irregular scaling artifacts of the commonly used VGA 320x200 mode (line doubled to 640x400 by every (S)VGA card) due to that mode's timing being indistinguishable from 720x400 VGA text mode. This may or may not be objectionable to you.
I tried to keep this brief, so I tried to mention only the most important points.
EDIT: Sorry for the typos. Writing this on a phone was not fun.