That was bad advice when mikee gave it and it's bad advice now. Don't take off your shield until you find a two-handed weapon or spells. Shield penalties to attack delay are not nearly that bad. And body armour penalties to weapons are completely meaningless (don't bring up how often you get "Your armour prevents you from hitting the X", that message is
literally a lie).
You're all talking about starting equipment, but the OP indicates complete disinterest in early game, not even training starting weapon skill. I'd suggest that the starting equipment and skills are not as important to them as you'd like. They specifically talk about getting 15 runes, even gladiator's throwing nets aren't likely to stick around
that long.
There's exactly one thing about backgrounds that has an effect later in the game: starting stats. Here's a little chart.
- Code:
Background Str Int Dex
AK, CK 4 4 4
AM 2 5 5
Ar 4 3 5
As 3 3 6
Be 9 -1 4
En 0 7 5
Fi 8 0 4
Gl 6 0 6
Hu 4 3 5
Mo 3 2 7
Sk 3 5 4
Tm 2 5 5
Wr 3 5 4
Wz -1 10 3
Other Mage 0 7 5
However, even this isn't likely to matter much: strength's effect on armour penalties has diminishing returns, and its effect on damage is awfully small, so once you have your spells at good success rates, more strength doesn't do much. Spell power has a brutal stepdown on it, effectively giving intelligence diminishing returns. Dexterity's effect on EV also has diminishing returns after 24, and its effect on stealth is small enough that it only matters earlier in the game (and only on stabbers).
So, mopl hinted at this already, but the answer is that for what you want to do, your background choice doesn't matter. If you really want you could pick Wz as insurance in case you find no +intelligence items. Between the two backgrounds you actually asked about, Fi and Gl, there really isn't a significant difference in early game power or in stats; both backgrounds even start with consumables! If really pressed I'd say Fi is currently better just because of better armour, but it's not a big difference.
Both backgrounds are a ton stronger than monk, though - monk has a worse weapon, worse armour, worse skills, no consumables, and the piety bonus does literally nothing until you actually find your altar. Really monk is one of the weakest backgrounds, only chaos knight is worse. Irrelevant later in the game, of course, but you will find it a lot harder to not die in early dungeon, particularly with Ds already being one of the worst early game species.