A crack, movement at the floor, or leaking base requires a different evaluation from a tank that simply keeps refilling.
Before comparing models, document the rough-in, floor condition, supply-stop condition, clearance, seat height preference, and whether the present complaint is flushing, leaking, noise, or comfort. A well-chosen fixture still needs a sound connection below it.
Keep this boundary: A new toilet is not a sewer-line diagnosis. Keep fixture replacement and downstream drain work separate until evidence connects them.