i think in terms of like backgrounds n stuff the most complex is a tie between these two
while most complex character drawing would be between these
(rpg games with gear gachas have a stronghold on me)
as for simple that's like...all my other art but in terms of most simple probably this one i guess
or like anything with mono
the bun bun was originally designed for that purpose specifically but it'll change a bit tho now that they're in a story
i think a lot of my drawings and even my own designs are fairly simple but when it comes to ones designed with a story or comics in mind i intentionally try to keep it simple since i'll be drawing them over n over n over again. otherwise when it's like one off illustrations or commissions i let myself go nuts 