I'm firmly in the smaller field camp, and I think the reasoning goes beyond just personal preference — there's a strong strategic case for it too.
The most obvious advantage is variance. In a large MTT with thousands of players, even if you're playing your best poker, the sheer number of all-in situations you need to survive to reach the money makes deep runs feel almost lottery-like at times. Your edge gets diluted over hundreds of
hands and dozens of opponents. Smaller fields compress that variance significantly, meaning your skill has a more direct impact on your results over a shorter sample.
There's also the ROI argument. Yes, big field tournaments offer massive prize pools, but the probability of cashing — let alone final tabling — is so low that your expected return per tournament is often not as impressive as it looks on paper. Smaller fields typically offer a better ratio of prize pool to field size, and you cash more frequently, which is important for bankroll stability.
From a strategic standpoint, smaller fields also allow you to gather reads faster and use that information more effectively throughout the tournament. In a massive field, you're constantly moving tables and starting from scratch with new opponents. In a smaller field, you spend more time with the same players, which rewards the kind of observational poker I enjoy most.