Many regard wood as the best construction material .... usually hardwood that has been 'harvested' responsibly.
Although the wood material choice usually means the conservatory will cost a bit more to build and attracts maintenance costs it does usually look very nice and natural. Wood often lends itself to those wanting more natural designs.
Being less conductive than aluminium a wood conservatory construction will not let as much cold air pass from outside to inside or indeed hot air from inside to outside.
When maintained properly a hardwood conservatory frame has a very good chance of looking better for longer than an aluminium conservatory frame, thus holding its value better.
Aluminium window frames tend to work out cheaper than hardwood, both in build costs and in maintenance costs. Maintenance costs exist but are minimal. For those wanting a thin profile structure then aluminium is better as it is very flexible, light and much stronger in thin strips than is wood.
When considering a design for your conservatory ask the supplier for help and make sure they are in a position to offer both options.
for more help with your conservatory, be it conservatory advice, conservatory repair or conservatory cleaning/valeting.