Steel is the best frame material for 95% of people due to its durability. Quality steel frames (not Schwinn travellers) are quite light. Cro-moly frames like Salsa are a good choice and weigh around 2-3 kg vs 1-2 kg for a carbon frame. There's plenty of framebuilders who can build custom frames out of other alloys as well. There's been steel frames built down to a kilo.
If you have a problem with harshness, wrap the bars with another layer of bar tape. Another option is to use wider lower PSI tires, preferably with wider 23mm rims. Not only is it softer, but the rolling resistance is actually less than standard road rims and tires.