I read manga more than I watch anime, and I read novels less than both. But I like all forms if they are done well.
As an artist myself I like reading manga because that is my target output so I appreciate the good quality even more and it's a nice reference for me as well.
Single-handedly doing animation is going to be the most time consuming medium choice, after all it's the only medium out of manga and novels and anime that require an entire studio to produce. If you want to try animation then doing test scenes will give you a good idea of your output rate. The specific animation style you mentioned is certainly less intense but still will require a lot of work, especially more than one episode per week. But the style itself is enjoyable, I've seen similar in the past as it was a good watch.
As for your speed I think 1 hour per page is fantastic!
Although your manga style is quite simple with minimal backgrounds so I think as you grow in experience you will want to add more details which will take more time, but that's down the line.
The issue is whether you can maintain that speed for 10+ hours a day (which is mad I must say) continuously to get through your story list as per your calculation.
I wouldn't bother comparing speeds with other artists (although I must admit I do the same!), because each person is different and will spend different amounts of time on each task. Just do the best you can do and you'll improve with time in everything

My manga project here took 30-45mins per page if you want to compare all the same XD
http://forums.mangaraiders.com/index.php/topic,20802.0.htmlkhahahaha 300 ideas? that's rookie numbers!! come back when you have 1000!!!!!!
just kidding!! Having a lot of ideas is what plagues a lot of creative types, although not many actually write their ideas down to keep a count. You might find that you can combine ideas together to reduce the overall story count as well. And having ideas that you yourself like I think is fairly common.
As for what medium is best, that depends on your motivation and targets.
Is this just a hobby thing or do you want fame and fortune?
For a hobby then just do whatever you enjoy the most, but if you're after making it a job then you've got to factor in what's popular with others.