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 I've seen many methods used to improve acceleration from a conditioning standpoint - uphill sprints, bounding, sled towing and Prowler pushing for example, but which work best?

Although acceleration requires greater foot/ground contact times compared to maximum speed sprinting - to impart sufficient force to overcome inertia - research indicates that better acceleration derives from quicker ground contacts. Spending too much time on the ground pushing or towing a heavy resistance will slow these forces and importantly significantly change sprint dynamics. 

Here's some research that considers jump squats.

Heavy vs Light Load Jump Squats

Twenty six athletic men with varying levels of resistance training experience performed sessions of jump squats with either 30% of 1 repetition maximum (the JS30 group - 9 members);  80% 1RM (the JS80 group - 10 members); or acted as controls (the C group - 7 members).
All the subjects performed an agility test, 20m sprint and jump squats with 30%, 55% and 80% of their 1RM’s before and after training.
Peak velocity, peak power, maximum jump height (JH), and average EMG activity for the concentric phase were calculated for the jumps.

​So what happened?

 The researchers discovered that there were significant increases in peak power and velocity in the 30%, 55%, and 80% jump squat performances of the JS30 group. This group also significantly improved their 1RM scores and crucially, showed improvements in their 20m sprint times. In contrast, while the JS80 jump squat group significantly increased both peak power and velocity in the 55% and 80% 1RM jump squat and significantly increased their 1RM’s, their 20m times were much slower.

This investigation indicates that training with light-load  jump squats improves acceleration. In contrast the heavier load did not benefit sprint acceleration - this is likely to be the result of the latter loads developing slower ground contacts and rate of force expression capability in the JS80 group.

So going heavy is not necessarily the answer, it's about the sprinter's ability to overcome inertia quickly with optimised ground reaction force and technique.
(There is a conundrum in all this - isn't there always - and I'll leave that for another day and another post. But suffice to say it's about maximum strength training (Bompa's MxS) and the desire to boost fast twitch motor unit recruitment with maximal neural excitement in a way that will transfer, largely from the weights' room to athletic performance. The training maturity of the athlete is also relevant in that the more mature they are, the more the  likelihood will be that heavy load strength training can boost performance... )
Ref:  J Strength Cond Res. 2002 Feb;16(1):75-82