You may not find all multi-tools convivial. I have gotten rid of as many as I have kept. Ones that try to do everything be limited at what they do well.

My current multi-tool happens to have a few hex keys. I use them in a pinch, but I also carry dedicated hex keys because they are easier to handle.

All of my tools fit, carefully packed, into a small sack slung under my saddle: my multi-tool du jour, a small crescent wrench, a small pair of needle-nose pliers, a hex key set, a tire patch kit, a spoke tightener (which I have never used), 3 plastic tire wrenches, and a vial of crazy glue. In my panniers, I keep a spare inner tube, a few feet of duct tape wrapped around a small tube of hand sanitizer, and a plastic bag of small spare parts (bolts, washers, etc.) I also have a Swiss Army knife, which I find I use quite often!