don't play who is strong.. finding a main isn't about "finding one one who will win you games" it is about finding someone you enjoy playing even if you're losing.
you need to know how good u are mechnially first, and compare that to how good you are intelligence wise.
do u outsmart your opponents? or do u have crazy orb walking skills.
if you have very good mechanics, you are goiugn to be better at mechnically intensives champs which take less "skill" but more "mechanics"
if u have less mechanics but can easily outsmart your opponents, then pick champs that have mroe skills and prediction
support is better for those who play the map and can predict and quickly judge skill levels of teammates and adc's accuratly to know when you can save somone and when u cant.
but support donest require much on "mechanics" just game knowledge
pick a champion that fits how u play.
for example. i have bad mechanics but a have TREMENDOUS game knowledge and can very easily outsart nearly every opponent i encounter... i can watch thier movements and predict to land skillshots.
i can even watch then enter fog of war and use thier movement speed and riot's build in pathing system to extremely accuratly predict what loation they will likely be and place a skillshot at that exact location when they should be there, even with no vision.
pick a champion that really speaks to you
i main nidalee, i always have.. she has been my main since day one
over 5 years later she is still my main.
my my champs pool has expanded but mostly includes similar champs
and even
on his ulti, make extremely good use of my ability to land skillshots that stop that the first target hit.
other champs i like to play but dont actaully play are

champs i have played with and tested and really liked by never really used and would learn of i got back into mid lane are

and champ i wouldnt mind learning like
but have never played.
there are also a few champs that i REALLY love but i cannot play becuase they fail to meet the requirements
for example is FAr too close to an ADC and too mechanically intensive for me to play. although i am VERY good with her ulti, and the strategy and timing behind it. i cant play the ranged auto attack part
strangly enough i also used to play
and
which dont seem to fit this pattern at all
but both of which are still "non mechanical" champs
a long while back riot also made this
https://na.leagueoflegends.com/en/page/find-your-lunch-table-which-champs-are-friends