If it is an enolate based reaction that uses an ester - like a Claisen condensation or malonic ester reaction - you can use the alkoxide that is the same as the ester - then if their is any reaction at the ester the product is the same as the reactant. Use ethoxide for ethyl esters, methoxide for methyl esters, and so on. The side reaction might happen, but it won't matter.
For other carbonyls, the alkoxide of choice is t-butoxide for the same reason - bulky and won't react as nucleophile with ketones. Sodium T-butoxide is a little easier to handle than LDA, and probably cheaper.