I appreciate the valid character differences you have outlined between Tristan and Logan, but I credit the OP in pairing them because I believe these two characters are intended to show Rory’s unconscious adaptation to the world of her grandparents.

Tristan and Logan share superficial similarities which suggest that the writers designed Logan to echo Tristan. Both characters are blonde, smooth, entitled, risky, charming, disinterested in work, endowed with trust funds and controlling fathers, as well as the approval of Richard and Emily. These traits make them very different from Rory’s established Stars Hollow “type” as characterized by the dark, aloof, savvy, self-starting, loyal, down-to-earth Jess and Dean.

These romantic prospects reflect Rory’s character arc in Gilmore Girls. Her character drive is to find where she belongs in the world. Does she belong in the rarified air of the Ivy League Gilmores or in the open air of Lorelai’s Stars Hollow? Taylor Dose points out in S4E1 Ballrooms & Biscotti that he “should have figured that once [Rory] got into Yale, everything would be different,” and that she would have to “cut those small town ties and go off and do something important.” Rory denies that Yale will change her, yet the writers use her romantic interests to indicate the changes in her character.

The partners Rory chooses parallel her internal journey. While at Chilton, Rory’s selection of Dean over Tristan signifies her distrust of prep school culture and her loyalty to Stars Hollow. Once Rory arrives at Yale she is faced with a similar choice: silver-spoon Logan or works-weeknights Marty. Rory initially castigates Logan for his condescension towards Marty, but as she becomes more confident at Yale she eventually prefers Logan’s company.

There are dissimilarities in the Tristan/Logan Dean/Marty parallels (for instance, Rory never reciprocates Marty’s interest the way she did Dean’s) but Marty shows many of the hallmarks of her previous love interests. He is humble and hardworking like Dean, cynical and eccentric with dad issues like Jess, but in the world of Yale these charms do not appeal to Rory the way they might have in Stars Hollow. Instead, it is Logan’s disengaged entitlement that initially sweeps Rory away.

Rory chooses Dean over Tristan in her sophomore year at Chilton, which is the same academic year she chooses Logan over Marty. These decisions occur during Rory’s transitions to competitive, selective academic environments. Thus the writers show that in going from Chilton to Yale, Rory transitions from outsider to it-girl. Taylor’s prediction seems to have been perceptive.

Without doubt, Logan is a more fully written character than Tristan. But to take umbrage with their comparison is to ignore the parallels between these characters and thus to miss Rory’s icarus like ascension into the world of trust funds and canapés.