My problem with free DAWs is consistency. Even if you've found one that fits your needs at the moment, there is no reassurance that any problem you may encounter in the future will ever get fixed. The updating frequency may be regular for now, but it can slow down to a halt eventually.
The only reason why all mainstream DAWs are such powerful tools for music production is competition. Their devs are people whose paychecks depend on the success of their product and that's a motivation you can bet on. The last thing they want is a bad reputation.
Free DAW devs have nothing to lose even if they get some money from it. They don't depend on the success of their product since they don't compete for a market share.
That said, I would love to use a free DAW (Reaper is not free) as my main production software despite some functional limitations.

 

These are the best freeware DAWs in the world

Cakewalk by Bandlab (formerly Sonar) (Win)
The DAW used to be called Sonar Platinum. Meanwhile, the brand name Cakewalk no longer belongs to Gibson, but to Bandlab and the DAW is completely free. For Windows, this is now the most comprehensive free DAW out there and more than just an insider tip. A lot of effects, amps, virtual synthesizers, tracks, functions, loops - but you need an account with Bandlab and the in-house download manager.

Studio One 4 Prime (Win, Mac)
Studio One 4 Prime is also an appetizer for the large versions of Studio One 4. The DAW is developed by former developers from Steinberg and Kristal. In the free Prime version you get an unlimited number of audio, MIDI, effects and buss tracks. You are limited to the 9 effect plug-ins you brought with you and the Presence XT sound generator and cannot install your own, but the DAW is definitely sufficient for sniffing and for first projects. A Presonus user account is mandatory.

Tracktion 7 (Win, Mac, Linux)
Tracktion has been publishing the older versions of their DAW of the same name for free for years. Meanwhile, the draft horse and Tracktion's successor is called Waveform, which is why Tracktion 7 is the last version to be completely free. The package not only includes a slightly different DAW with more intuitive operation (for beginners), but also a mixer, effects, editing functions and more. Tracktion also works cross-platform, which means that the DAW is available for Windows, macOS and Linux.

Music Maker Free (Win)
A very old representative and for some the entry into the world of digital audio production. In the meantime, you can no longer just push together loops and samples with Magix Music Maker, but also record and arrange your own things or compose with the sound generators you brought with you. You are limited to 8 tracks in the latest version, Music Maker 2020 Free. For Music Maker you have to create a user account with Magix.

LMMS (Win, Mac, Linux)
LMMS is called Linux MultiMedia Studio - this is due to the fact that it was initially only developed for Linux. The DAW is now also available for Windows and macOS. It is often referred to as the free alternative to FL Studio. The interface and thus the operation are also relatively similar. You can use it to record, arrange and mix audio and MIDI in the mixer without any problems. Editing is not that easy for us, but it is also possible. There are actually no artificial restrictions in LMMS as there are in other DAWs on this list. Whoever uses it should donate. You don't need a user account.

 

Tracktion is a really good daw. I fell in love with 7, bought 8 and I always upgrade to the latest version just to support those guys. One of the easiest daws to make music. I still use 11 for some projects.

 

One thing, though not free but still "free"...

If you've bought any music gear for a computer in the last, oh, 10 years or so, you probably have a license for Ableton Live Lite. It's very capable so you can't go wrong with that.

 

The same criticism can be easily leveled at paid DAWs, I'd think.