Depends on your budget. I have found the Meade 5000 series enhanced dielectric diagonal has worked well on my LX200 8". The Baader diagonals can be very nice and very expensive. I would check ebay and sometimes even places like Agena Astro in the US that have a good range and shipping cost is pretty good.
Bintel have a couple although their range is a lot smaller than I recall -
https://www.bintel.com.au/product-ca...her/diagonals/
Or you could watch the accessories section of the classifieds as diagonals do come up from time to time (or put a wanted ad up). Sometimes a well cared for secondhand diagonal does just as well with the bonus of cheaper cost.