FrogReaver
The most respectful and polite poster ever
I would personally say that Swashbuckler is easier to play than Arcane Trickster, but not HUGELY so. At 3rd level you only have very limited spellcasting, so it's not a huge issue of tracking and managing your spell resources.
I love magic and every character I play can cast something in some way either through Ritual Caster or Magic Initiate or class levels or both though, so I might be biased on how easy AT is or isn't for a new player.
Playing spellcasters isn't the problem - it's reading through all the dang spells and casting mechanics before you play them that is! Arcane trickster is easy to play - but not so easy to figure out what spells to take with him.