It depends on the situation and your other equipment.
For example: If you wear DD helmet and/or other DD accessories, you wont necessarily need a dol. Or if you have high resists, you wont necessarily need a scorpion shield.
The best is to buy a dol/dread/chitin/scorp and use the right shield in the right situation lol. Syphioric is only meant for lvl70- who cant afford chitin/dread (poor ppl like me, i have a Syphioric XD )