How long are you staying in Bali? Do you plan on staying in only one place? The 2 hotels you mentioned are in different areas, the Pansea Puri (cosy & romantic, the showers are outdoor in your own private garden) is in Jimbaran, where other 5 star resorts are located, i.e. the 4 Seasons, the Ritz-Carlton, & the Inter-Continental. In the same area is the Villa Hanani, smaller than the Pansea Puri, but equally nice. It has 4 villas (each with private swimming pool), but only 2 of the villas are right on the beach.

The Oberoi is in Seminyak, about 35-40 minutes by car from Jimbaran. Traffic between the 2 can be heavy at times. I think there are 4 rooms per building at the Oberoi, as opposed to the Pansea Puri, which each cottage/villa is by itself. The ocean at Seminyak can be rougher at times while at Jimbaran there is a reef. In my opinion, the Oberoi is more of an upscale resort hotel, while the Pansea Puri is more upscale boutique hotel.

If you plan on staying in Ubud, try looking into Puri Wulandari or the Pita Maha