MuchMoreThanMuscle saidYou should consume some healthy fats so avocados are good. I would switch out the peanuts for something like almonds or a true type of nut. Peanuts are not true nuts as they don't grow on trees and don't have as good of a nutrition profile as say, walnuts or Brazil nuts, etc.
Bananas are fine but not very high in nutrition. I recommend fruits with darker colors and something with skin. Apples are more nutritious than bananas and have less (fructose) sugar.
Bananas are good for their potassium, which needs to be replenished following certain activities where heavy sweating occurs. Those would include warm-weather running & biking.
Peanuts aren't bad, but there are other better choices as you say, and you can still do both. A question is whether to get salted, lightly salted, or unsalted when bought shelled. Despite the bad rap salt gets, it's a matter of what your own sodium levels are, along with other specific health issues you may have.
Because of my age and high blood pressure I was told to reduce salt intake. Well, when told to do something dietary for health I don't do half measures, and I avoided all salt. But then my next blood work was showing LOW sodium, and I was told to reintroduce some salt into my diet. So one of my munchies is lightly salted peanuts, a jar right next to this computer now.
Whole walnuts are another snack I keep in the kitchen. I crack the shells myself, as I find the shelled ones taste stale to me. They're a good source of omega-3 fatty acids. Despite the common belief that omega-3 is only an animal product (with the capsule form being called "fish oil"), it is in fact found in plants, as well. Walnuts are about the highest of the plant sources.
BTW, there's also an avocado ripening in the kitchen right now, that we bought at a fresh vegetable market yesterday, I'll check it today. Love avocados. I wouldn't know about gaining muscles, more interested in sustaining, and weight control, but I think those are all healthy foods in their own right.