All payment aggregators with PA/PG certification from RBI will have to follow similar guidelines. If your business is legit and your KYC is strong then none of the payment gateways will cause a problem from a settlement/blocking perspective.
Phonepe PayU and Razorpay all provide no convenience fees for the starting few months.
I think CCAvenue has the best pricing plans however razorpay's upside is the additional products that you can use which really helps start ups. PayU also has a very competitive pricing plan.
PhonePe on the other hand is more expensive.
I would suggest not to look at the payments flow and charges only cause those would be more or less the same, rather look into the reporting/recon/settlement/integration and additional products which are offered by the companies and which are aligned with the requirements of your org.