Across 984 ranked games on patch 16.21 in Master and above, Singed mains win 49.6% of their games in the top lane.
Their most common build appears in 36.1% of those games and wins 50.1% of its 355 games.
It starts 
Doran's Ring and 
two Health Potions, completes 
Liandry's Torment, 
Rylai's Crystal Scepter, 
Protoplasm Harness and 
Jak'Sho, The Protean in that order, and takes 
Boots of Swiftness.
Two other builds are played often enough in the top lane to be measured on their own.
In the top lane, Singed mains fare best against 
Nasus (won 65.0% of 20 games), 
Jax (won 66.7% of 15 games) and 
Urgot (won 64.3% of 14 games).
Their hardest matchups, the champions that counter Singed, are 
Yone (won 36.7% of 30 games), 
Gangplank (won 39.4% of 33 games) and 
Pantheon (won 38.5% of 26 games).