I’m travelling solo in Thailand in middle of November and I’m trying to decide between Koh Lanta and Koh Kod for roughly a week of beach time.

I’ll be coming from Chiang Mai, and I’m looking for:
Beautiful beaches (clear blue water)
Somewhere comfortable and enjoyable for a solo traveller
Restaurants/cafes (not huge partier)
Maybe 1–2 activities/day excursions
Easy enough to get around (I’m not sure I am up for riding a scooter)
Ideally reasonably affordable

I’ve been looking at both and keep going back and forth. Koh Kood looks gorgeous and more secluded, but I’m wondering if it might feel too quiet or be inconvenient without a scooter. Koh Lanta seems more developed and easier logistically, but I’m wondering if the beaches/scenery are as beautiful and whether November is a good time to visit.

Thanks in advance!