I've tried this. I'd go fighter because the class gives you the feats you need to max defence and have good offence.
Personally I tried a dwarven fighter with: str18/Dex15/Con14/Int08/Wis12/Cha05
Then go for weapon focus and the like. Yes, you won't be able to get secondary and tertiray attacks on your shield arm, but eventually you will be able to max your weapon focus, weapon specialization, shield bash tree and shield focus tree giving your shiled dwarf good defensive and offensive options both.
Results were good but it took me a while to pull this off.
I think that your best course of action depends on a lot of considerations (like point buy, what level you'll likely play to, and whether you'll go mythic or anything like that), but generally slayer is a great option... You can focus of strength and not worry much about Dex but still be able to get a ton of attacks (by choosing the ranger 2wf style), and studied target will offset 2wf penalties.
I think that your best course of action depends on a lot of considerations (like point buy, what level you'll likely play to, and whether you'll go mythic or anything like that), but generally slayer is a great option... You can focus of strength and not worry much about Dex but still be able to get a ton of attacks (by choosing the ranger 2wf style), and studied target will offset 2wf penalties.
Core, yo. No slayers allowed.
I'm going to say either Paladin or Fighter. If you're planning to go TWF-ish, then Fighter. Paladin will allow you to be a defensive house with the ability to pour on damage on-demand. Fighter will allow you to have slightly more consistent damage via TWF. If you are going the TWF route, you're better off with two heavy shields than the more iconic look of shield + waraxe.
The main case against Ranger is that you cannot wear heavy armor without shutting off your bonus feats.
I would wear medium armor, until you can afford Mithral Fullplate.
Go Ranger.
The way I read it, mithral does not bypass the Ranger's restriction on bonus feats from Combat Style.
The benefits of the ranger's chosen style feats apply only when he wears light, medium, or no armor. He loses all benefits of his combat style feats when wearing heavy armor.
Most mithral armors are one category lighter than normal for purposes of movement and other limitations. Heavy armors are treated as medium, and medium armors are treated as light, but light armors are still treated as light. This decrease does not apply to proficiency in wearing the armor. A character wearing mithral full plate must be proficient in wearing heavy armor to avoid adding the armor's check penalty on all his attack rolls and skill checks that involve moving.
My bad... I read 'core' and thought hardcovers... wasn't thinking CRB only. In that case, ranger.
Core? For this type of build? Go Fighter class. Ranger class doesn't have the Sword n' Board fighting style available. Even if you pick the two-weapon fighting style, you'll get more feats (and thus tricks) for your build.
Aside from that, I like the idea of taking a 2 level dip into rogue for evasion and an extra d6 on damage for flanking. The rogue combat trick could fetch you something nice too.
You explicitly can.
See this FAQ.
This is what I get for not checking the FAQ before posting.