Needing to replace replace what I have since it's falling apart. Anyway looking for something without a zipper and will keep whats inside dry. Also would rather not spend a ton of cash on it.
Needs to hold: 2 tubes multi tool tire levers 2 co2 canisters and the dispenser a little extra space for car keys
Jandd makes some nice bags. They are good quality, but not super high quality like one of the expensive boutique shops.. You can go to their website direct, or see if there are any good deals on eBay. https://www.jandd.com/
I just picked up an Ortlieb Saddle Pack, size Med. It will fit all of things you mentioned with a little room to spare. It mounts tightly to the bottom of the seatpost rails and straps onto the seatpost too. I've mounted and packed it full of stuff, but haven't ridden with it yet though.
I just upgraded from my 20 year old Specialized saddle bag to a Speedsleeve Ranger. It's far more compact, no zippers, easy on and off the bike and I'm impressed with it so far.
I really like my Arkel. The removable waterproof bag is very easy to use. When I first saw it I was a little luke warm about it but the more I use it the more I like it. At 50.00 dollars it is a little pricey but looks like it should last a very long time.
I've had good success with my specialized seat pack. The nice thing is it is expandable so you can make it larger if needed. Carried 2 tubes, 4 co2's, a multi tool, inflater head and a spare derailleur hanger in it last year at DK.
I found one on etsy. It's well made and the maker has many colors. I carry everything you do (sans one tube as I run tubeless) and it fits with room to spare. The cover flap allow me to roll up a gillet and fasten it to the back as well.