3 to a straight flush or a low pair?
Keep the low pair. On 9/6 Jacks or Better a pair of threes is worth 0.8237 per coin vs 0.6355 for the 6♥ 7♥ 8♥ straight-flush draw.
The exact numbers — 6♥ 7♥ 8♥ 3♣ 3♦
EVs are exact — every possible draw enumerated, not simulated — at max bet on 9/6 Jacks or Better. Check it yourself: the analyzer runs the same solver in your browser.
See all 32 holds of this hand ranked →Why
A three-card straight flush is the best-looking draw that isn't a royal — two ways to a 50-coin hand, plus flush and straight backup — and it still loses to the smallest pair. Two exact cards have to arrive for the 50-coin straight flush; the consolation prizes are a 6-coin flush and a 4-coin straight, and nothing here can pair into a paying high card. The low pair's ordinary trips-and-two-pair equity outruns all of that. Three-card straight-flush draws never outrank a made pair on this paytable — four-card ones do, and comfortably: line #4 sits above two pair.
Chart line #9 of 18 (low pair) sits above both straight-flush-draw lines: #11 (3 to a straight flush + high card) and #13 (3 to a straight flush, no high card). See the full solver-optimized strategy chart, or drill hands with exact-EV feedback until plays like this are automatic.