[Guide] Which Boxing Gloves Should I Buy?

these are all 14oz

When you start training in Muay Thai, Boxing, MMA or else, you will get to that moment where you are going to buy a pair of gloves, but you have no idea which brand, size or style of glove you need or you will like.

To make it simple I will suggest one to two pairs.

The Weight
You will use your gloves pads, bag or sparring.
When sparring is recommend to use a padded glove. A rule of thumb is if you are 70kg (160lbs) and over use 16oz gloves, if under go for 14oz. I wouldn't recommend to use anything under 14oz, especially if you are a bit heavy with your blows.
On bag and pads, you can go full power with your strikes and a lighter glove will be less bulky, lighter and have a better feedback when hitting. Anything under 12oz is fine. I have started training with 8oz on pads and love it!
But if you cannot afford two pairs, just get sparring ones; they will be fine on pads too. However, hitting the pads, and bag will make the padding to degrade more quickly, and some gyms may not recommend to use your pair of sparring gloves for pads and bag too.

The Brand
Most popular brand are good, some are more acclaimed than others, but all it comes down to preferences and costs.
Your gloves if treated well will last about two years average. Don't buy anything cheap, you will regret it soon enough and you will end up to change your gloves anyways.
I used to have cheap gloves and I hurt my wrist so many times, hopefully was never serious, but I risked an injury every times I did pads.
If you have had any problems with your gloves, you may look into gloves that protect a particular area of the hand more than another. Usually that comes down to wrist, thumb and knuckles.

The Comfort
This is a tricky one. Everyone has a different idea of what feels good or not. Thumb positioning is sometime an issue for some people (like in Cleto Reyes, Hayabusa). Another is the padding, both in shock absorption and feel, and of course the wrist.
There are two major style of gloves: mexican and thai.
Mexican have usually a longer cuff and a recurve thumb, while thai have a shorter one and a flat thumb. Gloves have various differences and each one will feel different to anyone.
Other things you may want to look into is how snug or roomy the compartment is, or wether your fingers will fit comfortably.
Three major thai brand are Top King, Twins and Fairtex.
Fairtex are my favourites, although I'm not sure people would like them better over Twins.
Fairtex are considered the most expensive of the three, but depending where you live you may see a more or a less price gap between brands. For example in UK the difference is minimal, but in Thailand I know that Fairtex cost twice as much as any other brand.
Fairtex is also the most compact glove of the three but also the one that is less snug, and you will have some room sideways.
I would say get Twins if you don't know what to get. They are snug, but not tight, while Top King are very very tight.
You need to give your gloves some time to break in and adapt to your hand. So, don't despise them right away, and see in a month how they feel.