Fusion TL minimizes the amount of things you need to trust. As long as you maintain your infinity balance you can safely stake with a third party with 0 risk of losing your FSN. In this case there's really only two things you need to trust 1. Yourself not to mess things up and 2. That the Fusion Blockchain keeps on running.
So, you don't need to worry about 1. The third party stealing your FSN and 2. Submiting FSN to a faulty smart contract. (Or at least you're only risking your chosen time-slices and not your full FSN. But since you're probably interested in gaining something from staking FSN, let's look at the various onchain pools and what their advantages and disadvantages are.
Node Networks - Is currently regarded as the most reliable pool for staking FSN. They don't only offer staking of FSN but also ADA. They also help produce some video marketing material both for Fusion and for AnySwap and are thus highly committed to the success of the Fusion ecosystem. Another advantage is that it's not a one-man operation. Both @JB_SE and @tayerr are committed to making it a great pool.
BitNordic - Is run by @ziefa. It has pools not just for FSN but for 7 or so different cryptocurrencies. It's as of yet a rather small pool for FSN, but has proven itself highly reliable with predictable end of the month payouts. As with Node Networks you're likely to get good service and help here.
GoFSN - Was the first and for a long time also the biggest pool for FSN staking. @gn1733388real who runs it used to be one of the largest investors of Fusion and a link between the Chinese and English speaking Fusion communities. Sadly @gn1733388real is less committed to Fusion than he once was and thus closed down "customer support" for his pool. The good news is that he's made it more advanced and 100% automated. So as long as you trust yourself, this is a really great pool as you can withdraw your TL stake at any time (something that is not possible in other pools). The result of this is (at least logically) that the overall yield would be lower for long term stakers, but that the pool could theoretically be used to extract value from less than 30 day TLs as well as be used for short-term interest yields, thus making it a true time value extractor. In order to withdraw from the pool you need to hook up to https://gofsn.com/ with Metamask configured to the Fusion network. Withdrawls also works with Ledger through Metamask, but not with other cold wallets. (Warning: Many users of GoFSN have had trouble with it lately and don't get help)
Pooltogether.io - Run by @MattG a marketing specialist who partook in the community marketing election 2020. His Fusion pool is as of yet rather small and untried water. But if you want to choose a pool based on increasing decentralization of the Fusion network, small pools such as this become a great choice. It's probably also quite easy to make a good special deal with a smaller pool.
Though I don't recommend this, several centralized exchanges also offer staking services for Fusion. I very much prefer the "DeFi" way, where you don't need to give trust to a third party, but for those who trust an exchange over themselves, this can also be an option.
This is more a staking platform than a CEX, but is connected to CEX liquidity and offers up FSN for sale in addition to staking. It's also like a CEX in that they will require full control of your FSN. Their goal seems to be making staking as easy as possible and offers staking for many different currencies in addition to FSN. This video explains how it works.
Hotbit has two options for staking FSN. 1. The lighter option where you gain interest simply by having FSN on Hotbit and 2. A locking option where you get a yield closer to the OnChain staking pools where you need to give them 7 days notice to withdraw your FSN.
MXC has a Fusion staking option, where I believe there's a minimum lockup period of 30 days.
Huobi has a staking option for Fusion that requires a 3 month lock-up minimum and which does not yield FSN but instead HPT. The yield rate is exttremely low compared to other options.
The only way to ensure full yield of staking is to run your own node. Check this tutorial on how to setup a node, also visit Fusionmining for guidance.