These are available ladders I most strongly believe in. I prefer wood folding ladders for simplicity and least cost.
Calvert USA, Manufacturing in Czech Republic, Distributor located in Solomons, MD. Their Products page.
Skywin Fakro, Manufacturing in Poland, Distributor located in Chatham. Ontario Their Products page. See them also for windows and skylights.
Conservation Technology, importer located in Baltimore, MD. Their page describing MidMade LUX A1120 ladders. See them also for green roof construction, and much more.
I have not tried the Rainbow wood ladder. Keeping a larger opening with ladder replacements, has doubtful advantage.
Rainbow, German components assembled in Connecticut, Known for heavy and expensive steel scissor extension. They also offer a wood ladder at the MidMade price, with advantage of filling 22.5x54, 25.5x54 and30x60 openings in replacing cheap, broken wood ladders.