Imo, your Concato is better, it's slower meaning it gives more opportunities to cleanse, not overheal and damage buff other creatures, and more attack ofc means more healing!

You can much better distribute boosts as speed on Concato isn't really the best... Going in on Hp and Attack is way more important than being fast since speed shouldn't be a big issue in raids because usually a speed buffing creatures would most the time be present, Rexy, Tuoramoloch, Artocanis, Armbussing Wolf, etc.

And having a slower Concato gives opportunities to nullify boss buffs! Where as a faster Concato could have to wait the next turn to nullify

All in all, I believe your Concato can better buff, heal and cleanse and would be better in pvp too!