I personally have never actually rode a horse, non other than a mere Mule, but, I am currently on a tennis team. Tennis is a very fun sport, shockingly not as boring as shown on tv. It's a good workout, keeps you active, and the feeling of knowing you hit an amazing shot just makes all of your work worth it.
So, I guess Tennis is better, in my opinion, so if you really want to play one of the two, I would highly suggest going with your gut on it. :) Hope I helped!
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