Dunlop Straplok Black Flush Mount

I'm not a fan of strap-lock buttons. Honestly, I prefer the "clip lock" strap solutions.
However, this set in particular has found a way into my heart.

The looks are amazing: you'll be able to find a perfect match to the hardware on your axe.
It is sturdy: it will stay in place no matter what.
It is easy to use: just press and attach... press and detach. Virtually, dummy proof.

It might be a little tricky to install, for on most situations you will have to trim the holes on your favourite strap. But other than that, it's just fine: place and attach the pressure-washer.

One thing that turns me down about strap-lock buttons is the size of them. However, Dunlop has tackled this issue by designing a female button that goes INTO your instrument! So, the end of it stays flush with the edges of your guitar or bass.
Yes, you have the inconvenience of having to drill the wholes a bit wider, but that's an fairly easy (albeit messy) job and once installed, you just forget everything about it.

I strongly recommend it!

Installed a set of these straploks on a customer bass, for the first time.
I like the fact they're virtually invisible once the strap is off but they require some pretty big hole in the horn of the instrument... if you put them on a thick finish body you're probably going to need some very good forstner drill bit to avoid tearing.
You'll also need a caliper to make the hole as deep as requested and not more!
I wouldn't leave an unexperienced player install these straploks on a decent instrument for sure.
The finish is good, though, and if you're sure you can live with straploks for your whole life, they can be a good choice.

I used Shaller S-Locks for the longest time and always liked them (not too big, very solid attachment) and came across the flush mounts a while ago.

I play a decent amount sitting down and some guitars (especially Vs but also some S-Type guitars) have the strap locks in positions that it pokes into the leg, which is not very comfortable.

The flush mounts completely remove that issue and I started moving all of my guitars over.

They feel as secure as the S-locks while being easier to unlock (since you press in the button rather than have to pull it up)

Only downside is that you need to drill a hole for them to seat into and so going from them to other ones is not as easy.