Edwin gets a lot of hype because he has the most powerful offensive capabilities of the mages AFAICT
I mean, it's really because he just has a fuckton of spellslots, which you can use for pretty much any relevant strat because his banned school is easily replacable. You can spam CC or you can be a nuker. Edwin is, on paper, better than your standard Conjurer CHARNAME just for that reason. I tend to prefer Imoen because you can dual her into a mage specialist and the Thief levels give more HP, bows, and she has a better stat spread.
however, BG isn't that complicated with regards to combat and for my playthrough I found it much more frustrating using Edwin over Minsc's girlfriend, as my mage was mostly using the white utility spells, Dispel Magic, Clairvoyance and Identify, and while Edwin has Dispel Magic he's pretty useless when it comes to those other two points. Clairvoyance dramatically reduces the frustration of searching big empty maps while identify is crucial for low-level and poor adventurers, both of which are likely more irrelevant for BG2.
Those are really QOL spells, though. I never once used Clairvoyance because it feels like a massive waste of a slot. At level 5, you'd prefer a Fireball to Clairvoyance. Clairvoyance also makes it annoying for when you actually *do* want to explore every single nook and cranny, because seeing the whole map from the start forces you to put in more effort to register where you've already been and where you haven't. If you're already insisting on running through all the wilderness maps, you might as well cast Haste on your entire party and just traverse the whole thing much faster, reducing the tedium much, much more. Whenever your party encounters some trash, Haste will help them dispatch it faster, or - if said trash is actually legitimately dangerous, you can retreat and regroup faster.
BG1 also seems to be more in-tune with letting the player character be a bog-standard fighter. The first big leap in power comes to the fighter when you get a +2 sword in chapter 2, and around that time you also get the Bracers of Dexterity which sends your AC plummeting, and you also get shield with +4 to missiles. I can't say I noticed any other class get so kitted out so quickly.
I'd argue it's the Cleric, because you can get Ashideena even faster than Varscona (Bassilus is a pushover if you choose the right dialogue options) and Clerics have really powerful level 1 spells and they continue to shine throughout BG1. Then again, a Mage also has a fuckton of useful things to do - Sleep is really overpowered in BG1, Mages can pick up the Evermemory ring in the secret stash in BG1 to just spam it at all times, and your Mage also gets the all-powerful Web, Haste and lots of AoE spells. Mage is the only character that can reliably take down challenges like the wraith that pops up if you try to loot Kozah's figurine (4000 XP). All that Mage has issues with is the very early game, as is in line with old AD&D - and he
still has absolutely amazing utility from level 1 just because of Sleep. A multi-mage party is really fun to play with, because you can mix and match - Edwin works really well with Xan and/or Xzar as support mages, where you can cast multiple spells on the battlefield at the same time. Mages also can use the most broken BG1 item ever, which is the Wand of Monster Summoning, which you can spam to trivialize any possible fight - or, in a frontliner-light team composition, simply provide support for your sole tank.
I honestly think your impression of the Fighter being pushed by is simply because Fighter is the simplest class to play, and also the tankiest, which makes it easier to avoid the dreaded animation of a disintegrating hand. Like, nobody goes to their first playthrough of BG1 and knows which spells are good, that Blind insta-wins encounters, that Blind can be used to reduce line of sight of all ranged characters to make them absolutely useless (including ankhegs - a level 1 Mage can farm those for carapaces and 975 XP apiece). Personally, I enjoy Fighter-types much more in BG2 than in BG1 - BG2 throws a ton of weapons with fun utility, like magical throwing axes, swords that possess decent enchantment and special effects (break out of Chateau Irenicus and you can almost instantly give your Fighter a sword that lets him cast Mirror Image, or a sword that makes him immune to status effects, or a sword that lets him annihilate the undead), and there are of course kits; Berserker is pretty straightforward, but a single-classed Kensai is nice for being a little trickier and fresher take on the class.
If you wanna eat your cake and have it too, make a Fighter -> Mage. Dual at level 4-5 just for a smoother start (we're not going full on powergaming here) and the access to bows and helms. You will be basically a tankier regular Mage. If you wanna keep the spellcasting flavor, Cleric -> Mage works too. You're not dualing for extensive spell lists in this case, you just want the early Cleric utility to have a smoother early run and you want to gain some bonus HP. Ofc, Thief -> Mage works very well too, as Imoen and Nalia showcase. You can go for something like Berserker/Mage for maximum cheese and crazy oh-shit buttons, but I tend to enjoy the self-restriction that dual-classers can't come from kits (Anomen is one of my favourite NPCs to play around with, barring his awful personality), especially if I'm making "primarily a Mage who enjoys some benefits from his former class" and not "absolute powerhouse with an answer to everything in the world". Dualling out early also means you will handily finish your new class in BG1 and will get to enjoy it without metagaming XP gains a lot in 2.
