I have searched a couple of resources about the implementation of Dapps, most of them redirected to ethereum itself. Is Ethereum the de facto platform for developing Dapps or do we have any other?
It's fair to say that Ethereum is the de facto standard for developing dApps but there are lots of other blockchain platforms out there, all with their own sets of use cases, languages, building blocks, digital asset types, consensus algorithms, and communities. Most platforms are not quite as mature as Ethereum just yet because Ethereum is the first to gain widespread adoption and usage. Additionally, many well-known coins are developing platform systems to enable developers to build smart contracts and dAapps alongside or on top of their networks.
At the time of this writing, here is some information that may be helpful for you (these lists are not comprehensive and this technology is constantly evolving):
Platforms with successfully deployed tokens on their network:
- Ethereum (ETH)
- Stellar (XLM)
- NEO (NEO)
- NEM (XEM)
- Ethereum Classic (ETC)
- Qtum (QTUM)
- BitShares (BTS)
- Waves (WAVES)
- Ardor (ARDR)
- Nxt (NXT)
- Ubiq (UBQ)
- Counterparty (XCP)
- Burst (BURST)
- Omni (OMNI)
- NuBits (USNBT)
Some other well-known platforms with a working concept, network, or application but to date, no deployed tokens and/or platform is in a beta/under construction stage and/or plans are in the works for a future dApp platform on the coin's network:
Again, these lists are not comprehensive and the ecosystem is evolving but this should give you a good idea. Keep in mind that most blockchain networks can be augmented and built upon since much of this code is open source and shared throughout the world. Even Bitcoin can have other tokens ride its blockchain using other types of platforms.
Lastly, just wanted to share my anecdotal experience with a few of the above platforms that I have had the time to dig in and get a feel for as a developer: I choose to write applications on Ethereum because it is the most widely adopted platform with tons of resources out there for us and is relatively inexpensive to deploy. Some platforms can either be very expensive in terms of network costs or very low in community resources. (Not naming names because I don't want to spread FUD) However, there are a few that in my opinion, have some really good resources and documentation and felt very welcoming for a developer in terms of costs and guidance. For me, these were Waves and Counterparty. Your mileage may vary and things are constantly changing so take that with a grain of salt. Do your homework.
Ultimately, there are plenty of platforms to choose from and it's a very exciting ecosystem. Go with the one that feels the best for you and allows you to write code right away. As long as you're coding, you've made the right choice.
There are rival coins that have similar functionality. Actually, even Bitcoin has scripting functionality, although quite limited and it's not used much (people basically don't know much about it).
Some other smart contract networks are Waves and Neo, but I think there are plenty of others also.
Ethereum is the biggest by far. You can estimate this based on coin's market value at https://coinmarketcap.com/tokens/ .