What do you look for the most in the dvd/bluray bonus features?

Audio commentaries, as I find them to be very informative

I always look to commentaries and gag reels first.Featurette's depend on the movie or actors involved.I agree about deleted scenes.There's rarely anything interesting there.

Audio commentaries.
Making of.. videos.

I get a bit disappointed when there's just a couple 2min featurette vids and that's it.

The Alien Quadrilogy and one of the Bladerunner releases with hours of in-depth, behind the scenes videos are what I love. As much information about the thought and design processes involved by the crew the better.

I also get a little disappointed when commentaries are too fluffy and offer no insight whatsoever into the inner workings of filming.

The behind the scenes bonus features i love to watch and it depends on what they are. As long they're not short like 6 minutes or whatever. I have heard for blu rays, that some of the main behind the scenes stuff are really long like from an hour or even 3 hours if its the old 3 disc Directors Cut of Rob Zombie Halloween.

cast commentaries and director and writer commentaries i like.

boring behind the scenes involving the art or CGI if they get too technical then im not gonna watch them

behind the scenes involving the music for the movies, eh... ill try to watch but skip

Gag reels and deleted scenes are the first things I go to. I do agree about deleted scenes, there's rarely anything they should've kept in.

I also enjoy "the making of..." certain scenes. Depending on the type of movie, they can generally be pretty boring. Entertaining and interesting when a good amount of stunts, special fx or CGI is involved though.

Commentaries and featurettes.

you know at the beginning of dvd i always thought wow audio commentary, what is that? how does that work? what is that like? i always thought it would be awesome to use but i don't think i've ever listened to that many audio commentaries. in my whole life i've listened to probably 10!!!
they don't seem that interesting or worthwhile. i think it's worthwhile though because oftentimes commentaries are really interesting.

deleted scenes mostly are a waste of time because they are pointless and are like watching non serious moments of actors talking to each other on the set while not filming. they always seem unprofessional. it's weird how that is. but deleted scenes are needed and essential for nudity and sex scenes that get cut. with a film like the wolf of wall street though nudity scenes deleted scenes aren't needed because it's jam packed with nudity.

featurettes are really cool though.

I always go for the deleted scenes first, I’m always curious what material was left out and second i go for behind the scenes and making off the movies.

Avengers EndGame had great bonus material in both aspects.
How they made many of the battles and all their deleted scenes were pretty cool.