Long post.
Depending on your needs you may consider the following streaming hardware options, from easy to more difficult. Option 8/9/10 can be easy to use but since I do not recommend them so they are put in the bottom.
For streaming I think Mi Box S should be a very good choice especially for new users. Then Nvidia Shield TV is another good choice if you are willing to pay for the performance. If for some reasons you do not like these two, you may want to consider Option 7, especially S905X3 boxes.
https://youtu.be/uzjC64FKzWo
The above is a good summary why Mi Box S is often recommended as the streaming device to go.
A) It is a streaming device which makes your TV smart or smarter than it is now. This is true for TVs like those Samsung Frozen OS based smart TV, LG Webos based smart TV and even Xiaomi TV running Patchwall Android based OS.
B)It runs official Google Certified Android TV OS which is easy to use.
C) Very good streaming support due to running Certified Android TV OS, Netflix 4K and YouTube 4K are supported.
D) Good voice remote with Google Assistant
E) Chromecast 4k function built-in. This is one of the best feature of Mi Box S. You can use apps like Netflix, YouTube, Starhub Go, SingTel TV Go, Singtel Cast, HBO Go, Viu Premium, etc, on the phone (iOS or Android) and then cast to your TV with this function. Basically this covers most of the popular Streaming services here in Singapore. Take note you can still use your phone for other things after the shows started on the TV. You can run Netflix, YouTube, SingTel TV Go and Singapore Cast on Mi Box S itself as well.
In terms of cost, typical cost in Lazada/Qoo10/Shopee is around S$70-90, depending on offer and coupon. Take note Chromecast Ultra (4k support) itself cost more than S$100. Even the cheaper Chromecast (1080p) costs more than S$50.
The main disadvantages of Mi Box S are the following.
a) The author mentions relatively weak CPU and occasionally lag or skip frame if you set the interface resolution as 4k. Still it is actually very good for streaming and even casual gaming due to good software optimization.
b) Relatively limited interface, only one USB 2.0 port and no Ethernet interface. Still take note the Dual Band AC WiFi works well.
c) Relatively small 8GB storage but you can add a fast USB Flash Drive to expand the storage
Nvidia Shield TV (usually S$200++) have all the advantages of Mi Box S and none of the disadvantages of Mi Box S.
Now we list down the options below.
1) Starhub fibre TV or SingTel TV
2) Starhub Go Streaming Box, running operator version of Android TV OS, not yet support Netflix but support Chromecast.
3) Google Chromecast dongles, including the 4k option called Chromecast Ultra
4) Apple TV and Apple TV 4k which are good option for Apple users
5) Mi Box S or Nvidia Shield TV running official Android TV OS whch supports Netflix 4k and YouTube 4k. They have built-in Chromecast 4K function as well.
You can load other apps as well with some exceptions like Starhub Go and Toggle. But you can use Starhub Go on the mobile and cast to TV. For Toggle, it works with Chromecast dongles but some users report issues casting with Mi Box S built-in Chromecast function.
6) Amazon Fire TV stick 4k or Amazon Fire TV Cube 2nd generation, which supports Netflix 4k as well, again you can side load other apps.
7) Other barebone Android TV boxes, say those from Zidoo, Minix, Beelink and Tanix. Or those generic boxes. No Netflix HD/4k support, no ChromeCast function.
Brand is one important factor in choosing the box. Android OS version and CPU/Memory/Storage/WiFi/Ethernet/etc are important factor as well.
Avoid 1GB memory boxes in this category for new purchases.
Amlogic S905X2/S905X3 and the older 905X/905L are pretty good choice in the medium end and Amlogic S905W is good at low end. Choose 2GB/16GB version for the low end.
2GB/4GB memory and 16/32GB/64GB are common for the new S905X2/S905X3 boxes and they usually run Android 8.x or newer. They also have dual band wifi, USB 3.0 port and 100M or gigabit Ethernet. S905X2 boxes were the most popular platform in year 2019. S905X3 boxes are the most popular boxes in 2020.
S905Y2 is basically S905X2 minus Ethernet. It is more meant for TV sticks but boxes can use it too.
S912 boxes are okay but S905X2/S905X3 have similar raw performance and better connectivity.
S905X3 is now popular, it is not much upgrade from S905X2 other than the CPU, but the price is getting lower even than S905X2 so you can get them now.
RK3318/RK3328 boxes are not as good now that S905X2/S905X3 come out. Amlogic S922X and Rockchip RK3399 boxes have the highest raw performance after Nvidia Shield TV but may not be worth the money as a streaming box.
Avoid Allwinner H6/H616 boxes unless for the preloaded boxes in the next section because of thermal issues. Their performance is also not as good as S905X3.
8) Preloaded boxes like UnblockTech Ubox with relative comprehensive live TV app UBTV and they try to support it even though UBTV is ordered by high court to be blocked by local ISPs. Not recommended but I can see why people still go for it. EVpad is another popular brand in this category.
9) Other preloaded boxes sold at Sim Lim Square, other shopping centres or online market place or even Facebook, most if not all are problematic and do not expect good support. Avoid them.
10) Not HW boxes but just paid IPTV subscription. Not recommended in general but I can understand why people buy them.
Of course there are other alternatives like smart TV from Samsung (Tizen OS), LG (Web OS) and Sony/Sharp/Philips (Android TV OS), among which Android TV OS is the smartest with more apps. Xiaomi TV China version is only recommended if you are only interested in mainland China content. There are Global version of Xiaomi TV as well but they may or may not have Netflix certification. So please make sure you contact the vendor for the details.
Then there are things like Roku box which is popular in US but may not be good for use in Singapore.
To summarize for year 2020.
Basically you can consider the following for sub S$100 boxes.
1) If you need Netflix or Chromecast, or SingTel Cast, SingTel TV Go, or TVB Anywhere+, get Mi Box S. Or if you want to pay, get Nvidia Shield TV 2019 non Pro (for streaming) or Pro (if you need gaming).
2) Consider Mi Box S again if you are first time buyer.
3) If you only need Netflix but not Chromecast, and you want to get a powerful box, get Amazon FireTV Cube 2nd Gen (2019 model). Amazon FireTV Stick 4K is also a good buy if you get the offer price of US$29 to US$39.
4) If you do not need Netflix, you can consider official Android TV OS boxes like Minix NEO T5 and Mecool KM3 and KM1.
5) If you do not need either Netflix or Chromecast, and you are an experienced user who know what you are doing, get new S905X3 boxes like the Beelink GT1 Mini 2.