Wide receivers, narrowly. Across 2022-2025, wide receivers scored 37.3% of all first touchdowns, running backs 33.9%, tight ends 15.0%, and quarterbacks 7.8%. Defensive and return touchdowns account for the remaining 5.7% or so.
This contradicts a common piece of betting folklore that running backs dominate the market at 40-45%. They don't. The passing game produces more first touchdowns than the ground game (56.1% of first TDs come through the air versus 38.3% on the ground). What running backs do offer is concentration: a team's carry leader is far easier to identify than its first-read receiver, which is why the shortest-priced player in most first-TD markets is a running back even though receivers as a group score more often.
The market prices this reasonably well at the top of the board. The value, in our experience, hides in the middle: red-zone tight ends whose inside-10 target share dwarfs their overall usage, and quarterbacks on sneak-heavy teams.
Source: 1,087 regular-season NFL games, 2022–2025, official play-by-play. Full method on the methodology page.