no need to overspend on vodka or gin if mixing, just like bourbons.
I happen to like Belvedere enough to sip it neat right out of the freezer, or with just a hint of vermouth in a martini, but for mixing and on the rocks, for short money Sobieski is pretty good, as is Lukasowa for potato vodka....Pinnacle, Three Olives, anything on sale, dump in tonic and ice, no problem.
I have similar feelings about gin, would rather use a gin with a little bite in a g&t, better than a smooth gin like Sapphire.
Smooth works better in a martini.
if available, Haymans Old Tom gin works in both. Old Tom style is sweeter than other styles of gin and smooth enough to drink on the rocks, very good in a g&t too. about $25 for a 750 here when it can be found...just say the word.
G&t"s and V&T's are great Summer cocktails.