Writing with no FS will not help. Avoiding some block will not help.
You can't solve the problem by speculation. Remember, "One fact is worth more than a 1000 speculations".
The SD standard has lots of alignment requirements for how to format the SD so that performance will be optimal. If you use the SD Association's formatter or my formatter, the SdFat SdFormatter.ino example, file structures will be properly aligned with erase groups.
You can't guess what the best policy will be. I have spent days trying and every card is different and the behavior varies with card use.
Only two things seem matter and the big thing is the SD card controller. If you have a good controller, you must use multi-block write and selecting write with pre-erase seems to help.
I added the ability to quickly create a large contiguous file to SdFat. Doing raw writes to these files is just as good as having no FS and access is easier on other computers. You have more flexibility than using something like dd. Multiples regions on one SD become a pain with dd.
Unfortunately cards with really good performance are no longer being manufactured. Cards that look the same have different controllers.
My best card was manufactured in 2007 and is a 2GB SanDisk Extreme III. This is version 8.0 of this model card.
The standard SD card (cards with 2GB or less) are being phased out.
Some SDHC cards perform fairly well with Arduino but again cards of the same model vary depending on the card version.
I have had good luck with some 4GB SanDisk Extreme cards.
Here are two examples, a 2GB card and a 4GB card. Notice that block groups on the 2GB card are much smaller than the 4GB card. 32 blocks vs 128 blocks. Also alignment of the FS partition on the 4GB card has a big unused space before the partition. The 2GB card has a smaller space before the FAT partition.
2GB Extreme III card:
Manufacturer ID: 0X3
OEM ID: SD
Product: SD02G
Version: 8.0
Serial number: 395023392
Manufacturing date: 11/2007
cardSize: 3970048 (512 byte blocks)
flashEraseSize: 32 blocks
eraseSingleBlock: true
SD Partition Table
part,boot,type,start,length
1,0X0,0X6,249,3969799
4GB Extreme HD Video card:
Manufacturer ID: 0X3
OEM ID: SD
Product: SD04G
Version: 8.0
Serial number: 3027274498
Manufacturing date: 4/2011
cardSize: 7744512 (512 byte blocks)
flashEraseSize: 128 blocks
eraseSingleBlock: true
SD Partition Table
part,boot,type,start,length
1,0X0,0XB,8192,7736320