PLC Compare is a valiant attempt to do a comparison of PLC brands and is useful to a point. However, unless you know every PLC really well (inside out) trying to compare chalk and cheese is almost impossible.
When I look there I see so many things missing/incorrect/do not knows that making a true comparison for a potential buyer is really not possible.
The people who put up the site really did a pretty good job but without the input of everyone who knows each brand of PLC really well it will never be a definitive comparison. Also I have no idea how all data would be assembled for readable assessment. There are things I look for in a PLC deep down such as some functions that I use all the time to make my life easy.
The site is, however, a really good 'first look' site - investigations then have to go a heck of a lot further.
For example, I program by I/O numbers and hate tags with a passion - they are too slow, so the tolls need to make programming this way from the keyboard quickly and easily is really important. Online programming also has to be quick and easy. Functions such as bit counters, linear approximation and quite a few other things are also important to me.
A major one is how easy is it to set up automatic data transfer between PLCs over Ethernet IP or another network? Extremely important when one has up to 20 or so PLCs all exchanging data on a network.
Different people will always look for different things.