What is the desired use?
You need batteries that fit the devices you plan to power.
Most solar chargers for small AAA,AA,C,D cell batteries do not really have enough solar to do any appreciable amount of charging.
For AAA and AA cells, the ENELOOP cells are ,in my opinion.the best
For 9 Volt,C and D cells,the TENERGY Low Self Discharge cells are a good choice...I use these.