DH and I will be in India and Nepal at the end of January and first few weeks of February. We were all set to spend a couple of nights in Ranthambore, but our India consultant, who has put the trip together for us, is currently in Sariska and emailed me this morning suggesting that as an alternative. Now I’m torn. I know that Ranthambore has more people, but it also has more tigers and that is the main objective. For those of you who have been to one or both, what do you recommend?

I have been to both these destinations quite a few times. My vote will go to Ranthambhore N.P. The reason is that not only the number of tigers is bigger there but also it is quite picturesque. The tree jungle and grasslands surrounding these lakes in Ranthambhore attract a lot of herbivores and the tigers follow them hiding in the grass lands. Normally, a tiger will be on the prowl at about 3 pm, after quenching his thirst, hiding in the scrub jungle and waiting for an opportunity to strike. This is also the time when the deer start feeding after resting during the day. There is hence a fair chance of seeing a tiger on an afternoon safari. There are some 150 types of Birds there. It is very photogenic with old monuments dotted here and there! Zones 1 to 5 are the oldest, well-protected and maintained and hence considered the best. You may occasionally see a leopard but these are usually found outside the gauntlet of tigers.
On the other hand, the topography of Sariska is quite different. The valleys & ravines within do hold a lot of game. But somehow, I have found Sariska a little spatially congested! Some years back, we spotted a wildboar stealing the kill of a tiger, darting in gingerly and scampering off with a bone, only to return. At dusk we heard the alarm calls of Sambhar getting closer & closer to the road from where we were watching the scene! We couldn't see the tiger as the time was up. The only time I have heard the alarm call of a Blue Bull is in Sariska, a very weird, piercing call, difficult to reproduce!
Indian jungles are full of adventure, whether it is Ranthambhore or Sariska.
Happy hunting!

Thank you for your answer. We are keeping the reservation at Ranthambore.

Ranthambore and Sariska Tiger Reserves are best spots for Tiger sightseeing in India. So, comparing Ranthambore vs Sariska is not good as both are very different from each other. If spotting a tiger is your main concern then it really does not matter which park you go to because the important factor is your luck of spotting a tiger at both places.
You can choose one of them to just spend a weekend in a greener environment.

Update: We spent two nights at Ranthambore, went on 4 drives, and had two very good tiger sightings. The first drive was fabulous, we saw a tiger that was only 8-10 feet away from us and we were with him for about 30 minutes. For the first 20 minutes, we were the only vehicle there. It was wonderful. On our last drive, we saw another tiger, maybe 25-35 feet away. Both sightings were thrilling. We also saw a leopard.

How lucky you were. Tigers and a leopard! I love your pictures, particularly the last one with the arched wall and tiger. It sounds like you had a great time.

We did three game drives in Ranthambore and just when we were about to give up on our last trip out, we had a great spotting of a tiger. They are amazing creatures.

The owner of the first picture looks like a big male tiger! Leopards are rare to sight sometimes you are just lucky.
Excellent & congratulations!