If you want the longest possible answer to this I have a 10k+ word google doc covering every game in the series except the most recent https://docs.google.com/document/d/18TMbTwoeAsOXadzSHsqzFp20-UbXIDq28-xbqoLg0Zc/edit?usp=sharing
The tldr is it depends on what you like.
If you're okay with extremely slow burn (to a fault) playing Sophie > Firis > Lydie&Suelle >Sophie2 will give you the series' most canonical lesbian relationship along with some very fun crafting (im very serious about the slow pacedness tho)
If you just want fun jrpg action and solid crafting with minimal jank the Ryza trilogy is that
If you want strong world building and a more serious tone than I recommend the Dusk games and esp Ayesha with a big asterisk that they're kind of high friction
If you enjoy old school suffering, tight time limits and possibly have a de-aging kink then play Rorona > Totori > Meruru
Imo it's hard to label worst games in the series bc they all have something to offer and downsides based on what you like. All the ryzas are kind of too easy. Sophie might be too hard. The depictions of non het sexuality in the Arland games are awful. Ayesha is too vague. Etc. Your results will be determined by what rubs you the wrong way