If you want a Diesel, go for the Ritz. It is one good frugal engine that will easily last over 2 Lac kms if maintained well.
OTOH, Alto K10 is a segment lower and a smaller car. It will be peppy but Ritz is the big daddy on the highways. I would pick the Ritz over the Alto K10
If you are planning for the Ritz at 3.4, why not that Zest at 3.5 Lac?