They are all pretty similar these days, most manufacturers have the same Italian machinery and press from the same steel. The only thing to watch for really is what are known as ECO rads (Economy not planet saving) which have thinner steel and shorter convector fins and thus shorter life cycle and lower heat outputs. There are also a few very old technology ones like the Screwfix Flomasta which has very thin waterways. The top manufacturers are constantly improving heat outputs with minor tweaks to waterways and convectors. Best way, check the heat outputs as this can often save a fortune (and space) because you can often go down a size.