Ignoring the Morrissey issue (for now, I certainly don’t ignore it generally) a straightforward 5 for me. The most important band of my teens and a genuinely brilliant, revelatory band on any terms. They probably sound less exciting to people who have only heard them retrospectively precisely because almost every indie guitar band that has followed has been massively influenced by them - their sound has become the default sound of ‘indie guitar music’ but that very much wasn’t the case at the time they emerged. There obviously were precursor bands (a lot of the Postcard bands, for instance) but ‘indie’ didn’t really exist as a genre (as opposed to a simple description of a means of distribution) when The Smiths started.
For me they were, for a short glorious period, almost a perfect band - clever, funny, moving lyrics, thrilling, catchy but deceptively complex music. They looked like a gang and had a swaggering, outsider chic to them. Everyone at my school hated them with a passion that it is hard to convey. Every time they appeared on Top of the Pops it sparked off a wave of mockery and derision that made me love them even more.
The quality of their songwriting in their first 18 months - 2 years of making records is just unsurpassed. Just remember that during that period they were putting songs like How Soon is Now? and Please, Please, Please on the B-Sides of singles because amazing songs were just pouring out of them.
In some ways their imperfections make them even greater - they never quite made a perfect studio album (the first record is appallingly produced and by the time of the later ones the songwriting has slipped slightly into formula at times). If you doubt them though just listen to Hatful of Hollow - basically the first 16 songs they wrote, recorded fast and dirty and 100% perfect from start to finish.