I've made video with both of these. On paper they're different animals - Higgsfield is a creative suite you make things in, fal.ai is a service you build products on - but fal has a playground that generates in the browser just like Higgsfield does, so comparing them directly is fair.
Neither trains the models. Both wrap the same ones - Kling, Seedance, Veo and the rest - so for a given model the output is the output. What you're choosing between is the wrapper and the pricing.
Pricing
Higgsfield is cheaper per clip, sometimes two or three times cheaper. But it's a subscription paid in credits, and the credits expire: whatever's left at the end of the month vanishes, and even top-up packs you've bought outright die 90 days after purchase. A quiet month and you've paid for nothing.
fal is metered. A price per second of video, listed per model before you commit, and nothing expires. It's probably not the cheapest metered option out there, but you're paying a bit extra for speed and reliability, which I think is the right trade.
My pick
fal. Partly the metering, and partly that Higgsfield's terms on refunds are not what I'd call fair - have a read of them before you subscribe. If you're publishing steadily and will genuinely exhaust your credits every month, Higgsfield works out cheaper. For anything bursty or unpredictable, which is most creative work I've seen, I'd use fal.