As you already know EOS tokens are available via exchange as well as via funding ether to EOS.io .
I'll suggest you buy EOS on exchange rather than funding ether to EOS.io for following reasons.
1. On exchange you can buy- sell immediately.
2. On exchange you'll know how many tokens you'll be getting per ether, while if you do funding on EOS.io ,you'll never know exactly how many EOS tokens you'll get per Ether. There are total 351 investment windows , out of which 8 already passed at the time I'm writing this post.
No of EOS tokens you'll be getting by funding Ethers in any funding window
=( Amount of Ethers Funded/Total Ethers Funded to EOS.io)*2000000
Any last minute huge amount of ethers can be funded and you'll end up getting less EOS tokens than you have guessed.
This is what happened with me and I suffered loss. Read my article to Know more.I funded Ether for Eos Tokens and Exchanged it Back to Ether all Within an Hour. Profit or Loss Cyle?
3. In funding process there are possibility of human made errors and if you are doing funding first time you'll need to learn few things before you'll be able to fund.Things like setting up ether wallet, sending Ether to EOS.io, claiming EOS tokens, adding custom EOS tokens , registering Key pair etc.
4. You can get EOS cheaper on exchange as per data up till now.
Let me know what do you think? How you got EOS tokens?