Both vaccines are effective.
There are no comparative trials with reliable results available at present to compare the two.
Covaxin second dose is given at 4 weeks.
Covishield second dose at 12 weeks.
Depending on local health care centre availability, and since you fall in the age group 18-44,
Covaxin second dose should will be available to you easily as compared to covishield.
( which is in shortage in some states for 18-44 age group)
Next Steps
Importantly, take the vaccine. ✌