Answer is, your own choice, All UPI can fulfil all needs, but for me it's SPay it allows me to use my cards without keeping them with me.. rest like UPI etc functions can be used here same.. other apps like Paytm, gpay or phonepe they are not just upi apps, they are now shopping gaming financial apps, investment, sip etc.. so I don't need them so I am okay with SPay
I use samsung pay, it's really handy, quick and easy to use but there is a draw back. Since Spay uses BHIM UPI it doesn't work well with PayTM, Gpay & PhonePe which are the most popular UPI platforms compared to Spay. The issue is that unless the receiver is using Spay or BHIM upi app they will not receive a notification when you send them money, not even an SMS. So when you send money to a small vendor/auto driver/a helper who doesn't have their bank app on their phone cannot check if they've actually received money so it becomes a hassle and causes distrust between you and the other party and I'm speaking from personal experience as it has happened to me a lot. Although this is not the case with large vendors or vendors who have speakers to notify them about any receipts.
That being said if I have to recommend I would recommend Paytm as that is the app and service very widely used. It also has the least amount of payment failures compared to other apps and there's data out there to prove it. PhonePe is a second good option and Gpay just had too many failures in my personal experience.
