bard mid
"actually pretty good" - phreak
i am an ok bard player and I've done some mid lane for a good week or 2. some builds are tried, some are still theoretical
x2 start
first item should be
or
(gunblade is preferable, scales better). almost always you should take
first back. instant thunderlords with this and a meep
burst build
(you can swap Abyssal for
if they have no AP threat )
tankier build

get
if you want to transition into a support (ie you're behind) to keep your utility relevant (you still need AP to make athene worthwhile at all on bard; if you go heavy tank then get censer or mikael )
AD reds to improve last hits, armor yellow (health if vs AP), scaling CDR blues (flat/scaling MR if vs a hard AP lane), AP quints
Thunderlords is always the best keystone but you can choose both the other trees for wherever you want the rest of your points. i suggest 12 in resolve for hard lanes; runic armor boosting heals is very good for surviving harder matchups
pros 2 sources of scaling: AP and chimes. getting both gives him very high mid-late game burst even with low-ish AP great early bully vs champs with the same or less range than him. squishies get chunked hard by his combo. can basically win the lane if you land a stun at level 1 versatile build path due to nature of his kit. full AP for burst or AP with some support items sprinkled in for utility great at turtling in lane thanks to W ult is great for countering all-ins from assassins and burst mages (assuming you avoid their cc)
cons
low range makes him struggle vs the likes of lux and xerath
no waveclear until he gets 25 chimes; early pushers can be a pain
nature of meeps makes it sometimes difficult to trade; you can be harassed a lot harder
hard to roam early for chimes because you can't abandon an ADC nobody will protect your turret. also chimes spawn on both sides of you; in top or bot they'll only spawn on one area relative to you
it's pretty good, give it a try