The thing I wouldn't like about starting out fighter is that it would slow down spellcasting (and the armor is actually worse so long as I have a +3 Dex mod or better). I'd have to wait another level for that big bump in power that comes from doubling your spell slots at third level, and I do have the arcane role to fill in the group. If I were to multiclass, I would want to stick with spellcasters, and I wouldn't want to plug more than one level into another class. (I'm going to need my ASIs). Warlock would offer armor of agathys, a few temporary HP from the fiend, and cantrips but no useful saves or proficiencies--and it still slows down spellcasting. Sorcerer, as much as I love it, provides very little for a single-level dip. Shillelagh would be weak with my (probable) 12 Wis, and . . . why else take druid?
That leaves bard and cleric. Both would get me a rapier, which is a good start. Bard would package with it a Dex save, bardic inspiration, and great low-level control spells (with a Cha-based DC, alas). Cleric offers shield proficiency, a nice range of spells including abjurations, and domains. Of these, only light and tempest have good first-level features which suit my purposes. (War would be good, if it played nicely with SCAG cantrips.) Both features would be limited by my lowish Wis, though. Tempest is the one which actually gets me the rapier, and the domain spells seem more interesting. If I took war caster at fifth level, I could have 18 AC (or 20 with shield of faith) and then the shield spell . . . or wrath of the storm for the one bum who still managed to hit me, and advantage on concentration saves.
Finalist #1: bard 1/abjurer X. More control, Dex save, less able to stand in and fight.
Finalist #2: tempest cleric 1/abjurer X. Greater variety of spells, higher AC, less control.
Finalist #3: abjurer X+1. Faster spell progression, less MAD, less versatility.