Your orchids look very healthy. Your vanda orchid looks like it might need a bit more air movement. The photo makes it appear to have a darkened trunk (not sure if that is fungus or just discoloration). Usually, I see vandas growing in open baskets or open pots, but some are grown in a pot like yours. I would suggest (if possible) you move this vanda to a more open container so that the roots and plant dry off after watering. Also, make sure you have plenty of air movement around your orchids.
As for the potting media in the other orchids, it appears to be new and fresh. Basically, the best medium for potting an orchid can be determined by your watering habits. If you like to water and do so often, you will want a potting medium that will drain rapidly and not hold as much moisture. If you don't water often, you may choose a denser medium that holds a bit more water for longer. This is also something that varies between different orchid varieties. Your dendrobiums have a thick cane that holds water and they therefore appreciate a medium that drys out completely --fairly rapidly. If you keep the roots of a dendrobium wet for too long, they will begin to rot away and your plant will show signs of distress (as if it is not getting enough water.)
Glad you were able to get photo posted. I hope other members here will also offer advice. I grow in a greenhouse and that setup is very different than one where the orchids are grown outside.
Good luck to you.