"We all go to the track. I run 440s. He runs 220s. The other guy runs 880s. We all get a big oxygen debt and we all improve. It's a lot of eyewash." Arthur Lydiard. Do whichever you like. Or do all of them. Just do them,or it.
Need way more context to say what is right today, tomorrow, next week, next month. All of these workouts are good & have their place.
For me, hills are in the base build with lots of strength (tempo/threshold work). Volume 800s would be an early season workout but 3 x 800 (mile) or 5-6 x 800 (3200) would be a good mid-season race specific workout. I always do a 6k-8k tempo & then hit the faster stuff that's part of a Mona fartlek. That can work basically any time of the year when you have a strength session on the calendar. Without the tempo, it's probably more of a race specific/even peaking type workout.
Mona Fartlek isn't a lot of volume, which is good for lower mileage runners. I tend to use it as a taper workout.
20 x 200m hills is overkill. Unless you're banging out really big miles, 8-12 will do just fine. You could even do 1 mile tempo, 8 x 200m Hills, 1 mile tempo.
How many 800m repeats and how much recovery? Is the recovery static, a jog, a float? These things matter.