I had an Ariston boiler & unvented 210 ltr cylinder in my last house so I know theyre good, but Ive moved & Im looking at combined boilers & cylinder all in one such as the Ideal istor HE 120 ltr or istor 80ltr, Alpha CD50 / 57 ltr, & Ariston Genus 30 plus / 50 ltr. Which, if any is suitable...