Great post!
Yeah, I think if you put in the same amount of money, your returns in Splinterlands could be as big as in Axie, maybe even bigger, because Axie seems more hyped to me, so prices should be higher than in Splinterlands.
I am not sure, but I think with $50 you are still stuck in Bronze league, if you are not renting. Bronze is terrible in Splinterlands! Would be similar to <800 (or maybe <1000) MMR in Axie, since the rewards are also not very high or not existing in that range.
To be honest, I didn't play Axie so far, but applied for a scholarship, since I cannot afford the high entry barrier right now. I definitely haven't made back my money invested in Splinterlands, but my assets did appreciate quite a bit and if I would sell them right now, I could realize some nice profits!
Wish you good luck on your journey and keep up the good work!