I think it depends on what kind of board you're going for.
If by 'fairly vanilla' you mean 'Province board with no serious megaturn potential' then probably, grab a Silver* and remake a copper. Copper's aren't that bad, Estates are, and Silvers are good.
*Or better $3, but at worst, a Silver
Consider the remainder of your deck in either case.
Remake 2x Copper. Your deck now has:
5 Copper
1 Silver
1 Remake
3 Estates
(Average card value is no better than you started the game, except you have a Remake)
Remake Copper, Estate. Your deck is now:
6 Copper
2 Silver
1 Remake
2 Estates
You have 1 more card in total, but your average card value is 0.91 instead of 0.7, which is a big jump. Okay, you have to consider the fact you probably get another $5 or a $4 next turn, before you reshuffle, which makes it slightly less extreme, but it's still much better to turn Estates into Silver than to trash copper for no benefit in almost all cases.
To put it in a more extreme way, suppose you instead drew RCCEE. It's pretty much the same scenario, but now you have three choices, and turning two Estates into two Silvers seems really, really good, while trashing two Coppers is a severely gimped Chapel.