I have a very desirable BabyBjörn highchair in lovely condition. It combines smart safety with modern design. Suitable from 6 months to 3 years, it easily adjusts as your child grows. Purchased for £200.
The adjustable safety table keeps them securely in place, preventing them from standing up and sits snuggly against the tummy to avoid food spills. The table is lockable with one hand, so it's ideal when your juggling tasks and there's no fumbling with tricky harnesses. The curved backrest hugs the body so that they stay comfortable and upright when sitting in the chair.
The smooth surfaces don't have hidden nooks and crannies, so they are easy to clean and the detachable tray can be hand-washed or popped in the dishwasher. It folds flat and is lightweight and convenient to take with you.