If it's your first time playing Baldur's Gate and you aren't familiar with the DnD ruleset I always recommend starting with either a fighter or ranger, simply because those two classes stay consistently useful and don't begin with any major disadvantages, unlike... well, a mage or bard which both begin as exceptionally weak characters. Hell the ranger is unarguably the most deadly class in Baldur's Gate, though they become less overpowered in BG2 and ToB. The bard never does become spectacular in any way either, fun to play and useful in a number of areas but they're exactly as advertised; jack of all trades but master of none. A mage by contrast by the end of Throne of Bhall is near godly in terms of power even if in Baldur's Gate they're nigh useless.
Now if you want to approach from a story perspective keep in mind each class has a unique set of missions and possible 'base' in Baldur's Gate 2. Fighters gain control of a keep, Paladin can join a paladin order, Druids a druid circle, mages get a neat dimensional portal thingy, thieves control a thieves guild, etc. Every class has one except barbarians, sorcerers, and I think monks who get shoved in with another classes story. Anyway that's worth planning in advance for if you know you want to play one consistent character through the entire series.
As for which make the most 'sense' story wise? They all kinda do, but I imagine mage, fighter, and cleric make the best argument given later revealed plot points. An argument could also be made for bards given where you begin though, but those three tend to make the most sense in my mind.