I'd say Gulliver's Travels is Swift's second-best book, behind Battle of the Books and a Tale of a Tub ( I think they were published together, but do not recall.) These are brilliant and learned--two qualities he did his best to suppress as he invented the novel, along with Defoe and Fielding. Tale contains a series of parodies, which of course I admired fifty years ago though I only published my own Parodies Lost recently, a biography of my brilliant parodist friend who especially parodied academic prose, as does Swift along with religious prose. His Tale is divided into three, the principal currents of Christianity in England in the late 17C, Peter (R.C.), Jack (for Baptists, Congregationalists, Presbytereans, and Quakers) and Martin for the author's own Anglicans. His satire here was seriously misconstrued, especially by the Queen, so that Swift's own advancement in his church was thwarted.
I have found my paperback from decades ago to quote a bit of Swift's brilliant parodies, a word he himself uses in introducing them. Of critics, he mentions Rymer and Dennis as well as Dryden's translation of Vergil, saying he himself was "plentifully instructed ...by a long course of useful study in prefaces and prologues"(331). Since my doctoral thesis was "This Critical Age," on criticism in verse, predominantly before Dryden, I find Swift very astute and amusing. On Lord Peter (Catholicism) he writes, "if Peter sent them abroad,...they would roar, spit and belch, and piss, and fart...till you flung them a bit of gold"; also, Peter would pardon Newgate prisoners for some coin, "whether he stand condemned for murder, sodomy, rape, incest, treason..." signed Emperor Peter (340). Note the priority of sodomy, pederasty, a centuries-old accusation of the Roman priesthood, though other religious, like modern American TV Southern Baptist preachers (say, Jimmy Swaggart or Jerry Folwell Jr.) are comparably hypocritical.
In Swift's ceremonious Conclusion to his Tale of (standing on) a Tub, he reflects on the "current relish of courteous readers" by observing "that a fly, driven from a honey-pot, will immediately, with very good appetite alight and finish his meal on excrement."(392) So much for good writing, as I have advised elsewhere on this site, "Avoid writing well. Too much work, and no-one notices."
Battle of the Books casts wonderful aspersions on Criticism (who is a goddess, daughter of Ignorance and Pride), in the battle of the Ancients and Moderns--Wotton, a modern, as is D'Avenant's modern epic Gondibert, which I read for my Ph. D. in 17C lit. but he also includes a grand three pages on the Spider and the Bee, Aesop- derived. "Upon the highest corner of a certain window, there dwelt a certain spider, swollen up to the first magnitude by the destruction of infinite numbers of flies, whose spoils lay scattered before the gates of his palace, like human bones before the cave of some giant"(404).
In the usu edition of Gulliver, Swift's elegy on himself witty and self-assessing, "Verses on the Death of Dr Swift" which starts with how we can stand enemies' success better than friends' (LaRouchefoucault, adversity of friends). Swift, "In Pope, I cannot read a line,/ But with a sigh, I wish it mine.../ It gives me such jealous fit, / I cry, pox take him, and his wit." Pox take puns on Pax tecum, the Latin mass, since Pope was a Roman Catholic, had to live ten miles from London. Later Swift's self-elegy, "My female friends, whose tender hearts,/ Have better learned to act their parts,/ Receive the news in doleful dumps,/ The Dean is dead, (And what is trumps?)/ Then Lord have mercy on his soul./ (Ladies, I'll venture for the vole [all the tricks].)/ Six deans they say must bear the pall./ (I wish I knew what king to call.)"
"On Poetry: A Rhapsody" records Swift against Dryden's Prefaces (which I thought superior), Rhymer, Dennis, and weak poets. "Say, Britain, could you ever boast,/ Three poets in an Age at most" (age= century?). "Remains a diffculty still,/ To purchase fame by writing ill." Many weak poets became lords, like Sir Richard Blackmore and Viscount William Grimston. "For, though in Nature depth and height / Are equally held infinite,/ In Potry the height we know;/ 'Tis only infinite below."