Having stayed at the Sheraton, Delta, and Courtyard multiple times, it's definitely between the Sheraton and the Delta:
- Sheraton - good location, generally better views as it's closer the Signal Hill and there are fewer tall buildings around, property is more dated, service can be friendly but haphazard and the front desk is often understaffed. They seem to give out upgrades randomly rather than prioritize by status - I've had multiple times where I've been given a parking lot view room and lower status family members checking in the same day have been upgraded to water views. The club lounge is OK, and the evening spread is generally pretty substantial, but it's often chaotic and poorly serviced during breakfast. In general, I find it's a poorly run hotel overall, and I get a sense of a lack of leadership throughout the property, but I do like the views and location.
- Delta - overall a better run hotel and they've done some renos recently. The hotel itself is a taller building, so has some nice views, but there's more tall offices around, and it's further from the Narrows, so the views overall are not quite as good. In general, I find the staff to be more organized and consistent vs. the more haphazard Sheraton, and they are better with recognizing status with upgrades.
The locations are basically on opposite ends of downtown, and I'd say it's a toss-up as far as location goes. In general, the Delta is a much better run hotel and more modern, but the Sheraton has better views. I'm spending time there this summer, and I'm splitting my time between the hotels (Sheraton at the start of the trip, Delta at the end), as it is really a toss-up.