Snakeman8, neither of those is a good first venomous snake. I have an albino cobra, and while I do find him beautiful, he is very difficult to work with. He is fast, aggressive, and not shy at all. Cobras require agility, speed, and knowledge of their movements to keep you safe, and even then they learn to predict your movements and take advantage of any routine.
Rattlesnakes are very toxic, and almost always cause semi-permanent or permanent tissue damage. They are more likely to retreat than cobras, but strikes are fast and bites are very potent. While some species are worse than others, none make a good first hot.
I would recommend looking into less potent snakes for first hots. While there is no really good first venomous snake, there are some that are less likely to cause you to die from a mistake. American copperheads (Agkistrodon contotrix spp.) are a good start if you want to work with rattlers later on. They are alert, quick and curious, and can be feisty. Most US hospitals stock Cro-Fab because copperheads and rattlers are indigenous in most of the states. A copperhead bite can cause joint damage, some necrosis, systemic sickness, coagulation problems, but is generally not as bad as a rattlesnake bite.
The best practice I found for cobras isn't a venomous snake at all...it's mean rat snakes. I love my Spilotes, and she is actually trickier to handle on a hook than a cobra. However, coral cobras (Aspidelaps) are a nice starter elapid. Their bites are not good, but unlikely to cause any permanent damage.
I hope this helps.