Both SBI Small Cap and HDFC small Cap have given very good returns over the past and can be conisdered for investment if you have a time horizon of 10 plus years. SBI Small cap has a slight edge over HDFC Small cap in the past but that need not hold true in future.
More importantly, before investing in any of these funds, please check if you have the appetite to take the risk associated with investing in small cap funds.
Get a free scientific risk profile done here.