My go-to breakfast has become oats for all the reasons you describe. I have a Pyrex (glass) bowl with a rubber lid. Every night before bed I put a cup of oats and a cup of water into the bowl and mix these together, then I add some frozen fruit on top, put the lid on the bowl, and stick it in the refrigerator. The next morning I top my oats with some no-fat Greek-style yogourt and a handful of nuts. If I have pumpkin or sunflower seeds and/or cacao nibs, I sprinkle a few of these on top as well. Voilà! Breakfast is ready to go! If I need to take it on the road, I just pop the lid back on the bowl, and I'm out the door.
1 cup oats = 21 grams protein + 12 grams fibre + 480 kCal
1/2 cup Greek style yogourt = 10 grams protein + 80 kCal
1/3 cup almonds = 10 grams protein + 6 grams fibre + 290 kCal
seeds are ~ 5 grams protein + 1 gram fibre per 100 kCal
the fruit adds some fibre and a tiny amount of protein as well
With the fruit and seeds added I figure this is around a 1000 kCal breakfast. So not calorie light for sure! But it has an excellent nutrition profile, and is filling and keeps me going all morning without any need for snacking. At 41 grams it's pretty great on the protein front. But if you needed more you could use milk (or a protein-fortified nut milk) in place of the water and/or mix some unsweetened protein powder into whatever liquid you choose.
I have eaten this almost daily for 10 weeks now, and I'm not bored of it yet. Which is saying something for me! I like a lot of variety and strong flavours in my food. With oats, I get the variety by changing up the type of fruit and other toppings I add.
Important to note: I only use whole, unadulterated fruits--usually frozen, because I like berries, and they're much less expensive where I live if purchased frozen. I don't use canned fruit because it has the peel (and therefore much of the fibre) stripped out, and also contains added sugars (as it's packed either in syrup or a super sweet fruit juice). One also needs to be careful with dried fruit. Unless it's a super sweet fruit (like grapes), dried fruit has sugar added to it as well. (Cranberries--which I love--have heaps of sugar added to them when sold dried.) I sometimes add a couple of chopped up dried apricots--which, like raisins, tend to be sold without added sugar--to my oats. But this is an occasional thing as they are a much sweeter fruit than berries.
For reference:
rhubarb contains 1.69 grams fibre per gram of sugar
raspberries contain 1.48 grams fibre per gram of sugar
cranberries contain 0.85 grams fibre per gram of sugar
strawberries contain 0.41 grams fibre per gram of sugar
blueberries contain 0.24 grams fibre per gram of sugar
apricots contain 0.14 grams fibre per gram of sugar
raisins contain 0.07 grams fibre per gram of sugar
dried cranberries (which are sweetened) are as bad as raisins on the fibre/sugar ratio: 0.07 grams fibre per gram of sugar
(This last one is going to depend on the amount of added sugar, which could vary from one brand to the next. I've used numbers from myfooddata.com to get the above ratios.)
So definitely all fruit is not created equal when it comes to their nutrition profiles.
eating like this for couple of years already 4-5 days a week