Often, it's a question of matching existing window frames but today's finishes can simulate natural or painted wood.
Aluminium frames are strongest, usually slimmest and available in well over 100 different colours - including a match for white pvc frames; PVC frames are available in wood-effect and can be the cheapest but you get what you pay for. Timber frames prices vary and the main reasons they are chosen despite higher maintenance issues is because wood can look good and because aluminium or pvc frames are not expected to match existing wooden frames on windows and doors.
There are many articles on the Internet and in magazines discussing this dilemma but even those written within the past year rarely include the alternative option - state-of-the-art FRAME-LESS patio doors. Only two manufacturers offer double-glazed FULLY RETRACTABLE patio doors that are thermally compliant with UK building regulations.
Compare SunSeeker Bi Folding, Frameless and UtraSlim frames:
Aluminium frames are available in a myriad of colours and it should be noted that frame-less double glazed doors have a visible seal at the sides of each panel.
All SunSeeker double-glazed French Doors and Patio Doors (i.e. Folding-Sliding and Slide-&-Pivot) adhere to British Building Regulations regarding thermal insulation properties.
If you require doors that do not need to be double-glazed - for example, as room dividers or to an orangery, single glazed frameless slide and pivot doors, originally called 'glass curtains' are the ultimate doors for sheer class - and that 'wow' factor!