The best thing is to NOT become a Vampire Lord at this point in time, if playing as a Dawnguard. You will still be able to talk to Serana and have her make you a vampire lord later in the game, so it's best to wait until you have finished all the Dawnguard sidequests. So for now, you should opt to become Soul Trapped.
Overall, the physical rewards (weapons, etc) are better if you choose Dawnguard. However, you cannot regularly use the powerful Vampire Lord form until after you've completed the main questline, or else the Dawnguard members will not accept you.
Amphibians can be divided into three groups: Urodela (salamanders), Anura (frogs), and Apoda (caecilians).
For this purpose, an IP address is recognized as consisting of two parts: the network prefix in the high-order bits and the remaining bits called the rest field, host identifier, or interface identifier (IPv6), used for host numbering within a network.