I just purchased Sonic 2, but I purchased Sonic 1 on accident from EBay. My question is, Is Sonic 1 worth keeping? Is it better than Sonic 2? And what are it's pros and cons? If not, I just plan to resell it on EBay.

I'm assuming you mean Sonic Adventure and Sonic Adventure 2 as this is the Dreamcast forum. The first game was quite enjoyable although personally I prefered the second, but then I hear quite a few people say they liked the first more. It's worth owning though, I mean as you've already bought it, you could try it out and if you don't like it re-sell it later. Unless it's sealed or something and you want to keep it sealed to re-sell for a reasonable price.

sorry i didn't make myself clear, but yes i do mean the Sonic Adventure series for Dreamcase. yes it is already sealed, and i don't want to open it unless it is really worth keeping. Sonic 2 is already being shipped to me, so I'm kinda curious if Sonic 1 is really worth keeping. I could probably sell it for more than what i purchased it for.

I can't really see the harm in keeping both, unless you really don't want it. I've seen a lot of new/sealed Sonic Adventure's on ebay for around $10.