When it comes to home studio monitors, it's a piece of studio equipment that everyone has an opinion on and when you think about it, the reason why is pretty obvious.
The shapes and sizes of our home studios are all different.
And the shape and size of a room has a huge impact on the performance of the monitors we're using.
In my previous studio space where I was close to a wall and in a corner the 8 inch monitors I now use would have been unbearable.
So whilst there are many variables that will affect the sound that we hear through our monitors, something we can make a educated decision on is the size of the monitor we choose to buy.
4.5 inch and below (think small box rooms and bedrooms)
I used a pair of Presonus Eris 4.5 monitors for a long time and having recently revisited them I still find them useable albeit somewhat abrasive in the upper mids and understandably a little lacking in the low end due to those 4.5 inch drivers.
But, if budget, or space is tight I think these still hold up and are certainly worth buying over the even more reasonably priced 3.5's which are I think, a stretch too far for critical listening.
5 - 6 inch (larger bedrooms and spare rooms)
Considered generally to be the sweet spot of home studio monitor size. This size driver delivers a revealing blend of low end oomph, detailed mid range and high end. Coupled with their 'fit in a bedroom' size, tuneable options and switchable variables like low end cut off, it makes this size monitor a very popular choice.
8 inch (open plan lounges, basements and long attics)
I've just recently been working on a pair of Kali audio 8 inch monitors and trying them out against the 6 inch pair I am surprised quite how much better they are translating. It's worth mentioning here that I'm working in a long attic which suits these really well delivering a fair bit more bass detail and a more open mid range.
In summary it is a bit of a tricky purchase as even checking out many different monitors in a music store isn't going to tell you exactly how well they'll translate back in your home studio. Ultimately, do your research, make your choice and don't look back. Allow yourself time to get used to your monitors and get on making awesome music!