As an idea, flats: Chromes are one end of the spectrum being bright, GHS Precision flats being dark or mellow.
For Rounds, a Stainless steel will be bright, something like a GHS boomer will be more mellow. Some place there the chromes and boomers may be close to the same sound to some ears.
Used flats can be had in the classifieds here on TB, a great way to try those at a reduced price
Jazz #1200 / Precision #1131/ Colorado #327/ Fender Rumble #327