if backlinks are the ONLY thing you need it for, majestic is the best value by a distance — the whole index is links, so you're not paying for keyword/rank features you won't touch, and trust flow / topical trust flow is underrated for spotting which of a competitor's links are actually relevant vs just numerous.
but for competitor analysis you can honestly get most of the way on free tiers stacked: ahrefs' free backlink checker (top 100 by domain), moz link explorer (a few checks a day), majestic's free view. run a competitor through two of them and you've mapped their strongest links for nothing.
the part nobody mentions: the tool is the cheap bit, the value is in what you throw away. a competitor's raw profile is 80–90% noise you can't or shouldn't copy — expired junk, scraped directories, links on dead pages. export it and keep only the links that are ********, on a topically relevant page, and on a URL that's itself indexed / gets traffic. that shortlist is the only part worth chasing, and any of the cheap tools can show it if you sort by it. paying for a bigger index just buys you a longer list of junk to filter.
one caveat: budget tools have smaller, staler indexes — so before you decide a competitor doesn't have some link, cross-check on a second one. no single cheap crawler sees everything.