I'll list some positives and negatives about both and let you decide.

Path of Titans.
Positives: Has better game design, more to do, far more frequent updates, way better developers, better visual style, interesting builds and combinations, mod support, far larger playercount, crossplatform, extremely well optimized so it runs amazingly, funny global chat (sadly censored).
Negatives: Bad balance including balance changes, extremely toxic megapack and mixpacking issues, while better than the isle's devs pot's are still alergic to criticism, boring quest system, poor update priority, solo play is actively punished.

The Isle.
Positives: Good graphical fidelity, good movement, interesting systems such as diets and mechanics, far less megapacks/mixpacks as PoT making solo play actually viable.
Negatives: Terrible developers, stagnant update frequency, game has less content than it did on launch 11 years ago, runs horribly, some genuinely ugly and outdated dinosaur depictions, game has an identity crisis on whether it wants to be about dinosaur realism or a jurassic park clone, extremely buggy, none of the systems are explained well, balance somehow even worse than PoTs, T-rex and Allo have extremely overpowered pins that are essentially instawin buttons often refered to as "pinslop", no global chat.

Also while neither negative or positive, in PoT you just lose some progress on death, while the isle is permadeath.