Hi. This usually depends on the goal you want to achieve. You want to finish one of your projects I guess.
If you feel confident about having the skills to finish every title in your sketchbook i'd stick to the most uncommon and innovative one. Just be sure there is a base of gamers out there wanting to play it. Coming up with something never seen before will catch the most attention.
There will be even a more critical feedback on your work, since no one would pay the same attention to the 100st clone of an already released game.
Sure it can be a clone, but there should be some new aspects or features in it to show up between the other titles.
Have something like that? Stick to it!