Equibase, Daily Racing Form (DRF), Brisnet and TimeformUS all build their past performances from the same underlying official race data. What you're actually paying for when you buy one over another is the speed figure, the pace information and the extra statistics each company layers on top, since every one of them uses its own proprietary numbers rather than a shared industry standard.

What each one sells, and what it prints

Source Typical price Its own figure
Equibase $1.50 (basic) to $2.50 (full PDF); $8 for a horse's lifetime record No proprietary speed figure; the free and lowest-cost option, with fewer analytical extras
Daily Racing Form (DRF) $4.95 for one track, $9.45 for three The Beyer Speed Figure, adjusted for the track's own speed that day; pace figures in its premium Formulator product
Brisnet (BRIS) Around $3 a card Its own computer-based speed rating, plus E1/E2/LP pace ratings and a combined 'Prime Power' ranking
TimeformUS Around $3 a card Its own speed figure, adjusted for how the race's pace actually unfolded, plus jockey and trainer ratings out of 100

ADW betting platforms (TwinSpires, FanDuel Racing, NYRA Bets and others) commonly include past performances free with a funded account, which is often the cheapest way to get a usable set if you're already betting through one of them.

Which one to pick

None of these is simply "better"; they differ in what they emphasize. Brisnet leans toward pace shape and breeding data (sire and damsire statistics). TimeformUS leans toward visual, pace-adjusted figures and separately rates the jockey and trainer. DRF's Beyer figure is the one most commonly referenced in racing media, which makes it a reasonable default if you want your numbers to match what you read elsewhere.

Whichever you choose, the format is close enough across all four that learning to read one past performance line carries over to the others; only the speed figure's name and scale change. The beginner's guide to handicapping covers what to do with the figures once you have them.