Is it better to spam heroes that have success in your own bracket (3k) or pro level?

I play position 1 and would like to spam a pool of 3-5 heroes to try and improve my MMR. Naturally, I would say that I have the best chance of winning games with the heroes that work in my own bracket (Legend 3).

However, could this high win rate just be down to the simplicity of the hero’s kit/play style?

For example, spectre does well in low mmr, but she is pretty easy to play and games tend to go later in this bracket.

The point I’m getting at is, if I were to spam a hero such as carry Lina, who is a bit more technically difficult and doesn’t seem to do as well in low MMR (the reason for this I am not too sure).

Is this not a a better idea as the hero is stronger on paper (has a high win rate with pros but is maybe just a bit more difficult to pull off which could explain her win rate in low MMR). Would this be a better strategy in the long run, I would just need plenty of practice on the hero?

Thanks in advance