It really depends on what you will use the two social networks for. If you are planning on using it to get traffic, I would definitely recommend using Twitter because they have been known to get a lot of traffic to a website. If you just want to connect to users and maybe get some minor traffic to your site, I would recommend fizzlive. Twitter however, has the potential to generate some major traffic depending on the business you have. Also twitter has a higher PR than fizzlive. I personally use Twitter as well.
Twitter is much better know so its range is a way wider. Yet I wouldn't limit myself just to Twitter. There may be other networks that are more popular in your region - one of them may be FizzLive!
twitter is really working for me and fizzlive, i never heard and visit the site so from my side its zero no. twitter, facebook are good source of traffic.
Twitter is the best social networking website. It give huge unique visitor to any website. Almost all webmaster use twitter to gain more organic traffic to any website. I am never hear about fizzlive before. So, I don't any idea about .But I am use twitter regularly to increase traffic of my website.
Well twitter is bigger network 500 000 000 registered users so you cant avoid it if you plan to do serious business
Actually same social site isn't perfect for all types of site. I believe twitter is better than fizzlive in 80% types of site.
Twitter is better right now simply due to the amount of exposure you can get with it. Fizzlive is still new and its member base is still growing but it's too small by comparrison to Twitter. The more exposure you can get your sites the better your Social Impact will be.